text: // Copyright 2011 The Chromium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #include "cc/trees/damage_tracker.h"
  
  #include <stddef.h>
  
  #include "cc/base/math_util.h"
  #include "cc/layers/layer_impl.h"
  #include "cc/paint/filter_operation.h"
  #include "cc/paint/filter_operations.h"
  #include "cc/test/fake_impl_task_runner_provider.h"
  #include "cc/test/fake_layer_tree_host_impl.h"
  #include "cc/test/geometry_test_utils.h"
  #include "cc/test/layer_test_common.h"
  #include "cc/test/test_task_graph_runner.h"
  #include "cc/trees/layer_tree_host_common.h"
  #include "cc/trees/layer_tree_impl.h"
  #include "cc/trees/single_thread_proxy.h"
  #include "testing/gtest/include/gtest/gtest.h"
  #include "ui/gfx/geometry/quad_f.h"
  #include "ui/gfx/geometry/rect_conversions.h"
  
  namespace cc {
  namespace {
  
  void ExecuteCalculateDrawProperties(LayerImpl* root,
                                      float device_scale_factor,
                                      RenderSurfaceList* render_surface_list) {
    // Sanity check: The test itself should create the root layer's render
    //               surface, so that the surface (and its damage tracker) can
    //               persist across multiple calls to this function.
    ASSERT_FALSE(render_surface_list->size());
  
    LayerTreeHostCommon::CalcDrawPropsImplInputsForTesting inputs(
        root, root->bounds(), device_scale_factor, render_surface_list);
    LayerTreeHostCommon::CalculateDrawPropertiesForTesting(&inputs);
    ASSERT_TRUE(GetRenderSurface(root));
  }
  
  void ClearDamageForAllSurfaces(LayerImpl* root) {
    for (auto* layer : *root->layer_tree_impl()) {
      if (GetRenderSurface(layer))
        GetRenderSurface(layer)->damage_tracker()->DidDrawDamagedArea();
    }
  }
  
  void EmulateDrawingOneFrame(LayerImpl* root, float device_scale_factor = 1.f) {
    // This emulates only steps that are relevant to testing the damage tracker:
    //   1. computing the render passes and layerlists
    //   2. updating all damage trackers in the correct order
    //   3. resetting all update_rects and property_changed flags for all layers
    //      and surfaces.
  
    RenderSurfaceList render_surface_list;
    ExecuteCalculateDrawProperties(root, device_scale_factor,
                                   &render_surface_list);
  
    DamageTracker::UpdateDamageTracking(root->layer_tree_impl(),
                                        render_surface_list);
  
    root->layer_tree_impl()->ResetAllChangeTracking();
  }
  
  class DamageTrackerTest : public testing::Test {
   public:
    DamageTrackerTest()
        : host_impl_(&task_runner_provider_, &task_graph_runner_) {}
  
    LayerImpl* CreateTestTreeWithOneSurface(int number_of_children) {
      host_impl_.active_tree()->DetachLayers();
      std::unique_ptr<LayerImpl> root =
          LayerImpl::Create(host_impl_.active_tree(), 1);
  
      root->SetPosition(gfx::PointF());
      root->SetBounds(gfx::Size(500, 500));
      root->SetDrawsContent(true);
      root->test_properties()->force_render_surface = true;
  
      for (int i = 0; i < number_of_children; ++i) {
        std::unique_ptr<LayerImpl> child =
            LayerImpl::Create(host_impl_.active_tree(), 2 + i);
        child->SetPosition(gfx::PointF(100.f, 100.f));
        child->SetBounds(gfx::Size(30, 30));
        child->SetDrawsContent(true);
        root->test_properties()->AddChild(std::move(child));
      }
      host_impl_.active_tree()->SetRootLayerForTesting(std::move(root));
      host_impl_.active_tree()->SetElementIdsForTesting();
  
      return host_impl_.active_tree()->root_layer_for_testing();
    }
  
    LayerImpl* CreateTestTreeWithTwoSurfaces() {
      // This test tree has two render surfaces: one for the root, and one for
      // child1. Additionally, the root has a second child layer, and child1 has
      // two children of its own.
  
      host_impl_.active_tree()->DetachLayers();
      std::unique_ptr<LayerImpl> root =
          LayerImpl::Create(host_impl_.active_tree(), 1);
      std::unique_ptr<LayerImpl> child1 =
          LayerImpl::Create(host_impl_.active_tree(), 2);
      std::unique_ptr<LayerImpl> child2 =
          LayerImpl::Create(host_impl_.active_tree(), 3);
      std::unique_ptr<LayerImpl> grand_child1 =
          LayerImpl::Create(host_impl_.active_tree(), 4);
      std::unique_ptr<LayerImpl> grand_child2 =
          LayerImpl::Create(host_impl_.active_tree(), 5);
  
      root->SetPosition(gfx::PointF());
      root->SetBounds(gfx::Size(500, 500));
      root->SetDrawsContent(true);
      root->test_properties()->force_render_surface = true;
  
      child1->SetPosition(gfx::PointF(100.f, 100.f));
      child1->SetBounds(gfx::Size(30, 30));
      // With a child that draws_content, opacity will cause the layer to create
      // its own RenderSurface. This layer does not draw, but is intended to
      // create its own RenderSurface.
      child1->SetDrawsContent(false);
      child1->test_properties()->force_render_surface = true;
  
      child2->SetPosition(gfx::PointF(11.f, 11.f));
      child2->SetBounds(gfx::Size(18, 18));
      child2->SetDrawsContent(true);
  
      grand_child1->SetPosition(gfx::PointF(200.f, 200.f));
      grand_child1->SetBounds(gfx::Size(6, 8));
      grand_child1->SetDrawsContent(true);
  
      grand_child2->SetPosition(gfx::PointF(190.f, 190.f));
      grand_child2->SetBounds(gfx::Size(6, 8));
      grand_child2->SetDrawsContent(true);
  
      child1->test_properties()->AddChild(std::move(grand_child1));
      child1->test_properties()->AddChild(std::move(grand_child2));
      root->test_properties()->AddChild(std::move(child1));
      root->test_properties()->AddChild(std::move(child2));
      host_impl_.active_tree()->SetRootLayerForTesting(std::move(root));
      host_impl_.active_tree()->SetElementIdsForTesting();
  
      return host_impl_.active_tree()->root_layer_for_testing();
    }
  
    LayerImpl* CreateAndSetUpTestTreeWithOneSurface(int number_of_children = 1) {
      LayerImpl* root = CreateTestTreeWithOneSurface(number_of_children);
  
      // Setup includes going past the first frame which always damages
      // everything, so that we can actually perform specific tests.
      root->layer_tree_impl()->property_trees()->needs_rebuild = true;
      EmulateDrawingOneFrame(root);
  
      return root;
    }
  
    LayerImpl* CreateAndSetUpTestTreeWithTwoSurfaces() {
      LayerImpl* root = CreateTestTreeWithTwoSurfaces();
  
      // Setup includes going past the first frame which always damages
      // everything, so that we can actually perform specific tests.
      root->layer_tree_impl()->property_trees()->needs_rebuild = true;
      EmulateDrawingOneFrame(root);
  
      return root;
    }
  
   protected:
    FakeImplTaskRunnerProvider task_runner_provider_;
    TestTaskGraphRunner task_graph_runner_;
    FakeLayerTreeHostImpl host_impl_;
  };
  
  TEST_F(DamageTrackerTest, SanityCheckTestTreeWithOneSurface) {
    // Sanity check that the simple test tree will actually produce the expected
    // render surfaces.
  
    LayerImpl* root = CreateAndSetUpTestTreeWithOneSurface();
    LayerImpl* child = root->test_properties()->children[0];
  
    EXPECT_EQ(2, GetRenderSurface(root)->num_contributors());
    EXPECT_TRUE(root->contributes_to_drawn_render_surface());
    EXPECT_TRUE(child->contributes_to_drawn_render_surface());
  
    gfx::Rect root_damage_rect;
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
  
    EXPECT_EQ(gfx::Rect(500, 500).ToString(), root_damage_rect.ToString());
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, SanityCheckTestTreeWithTwoSurfaces) {
    // Sanity check that the complex test tree will actually produce the expected
    // render surfaces.
  
    LayerImpl* root = CreateAndSetUpTestTreeWithTwoSurfaces();
  
    LayerImpl* child1 = root->test_properties()->children[0];
    LayerImpl* child2 = root->test_properties()->children[1];
  
    gfx::Rect child_damage_rect;
    EXPECT_TRUE(GetRenderSurface(child1)->damage_tracker()->GetDamageRectIfValid(
        &child_damage_rect));
    gfx::Rect root_damage_rect;
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
  
    EXPECT_NE(GetRenderSurface(child1), GetRenderSurface(root));
    EXPECT_EQ(GetRenderSurface(child2), GetRenderSurface(root));
    EXPECT_EQ(3, GetRenderSurface(root)->num_contributors());
    EXPECT_EQ(2, GetRenderSurface(child1)->num_contributors());
  
    // The render surface for child1 only has a content_rect that encloses
    // grand_child1 and grand_child2, because child1 does not draw content.
    EXPECT_EQ(gfx::Rect(190, 190, 16, 18).ToString(),
              child_damage_rect.ToString());
    EXPECT_EQ(gfx::Rect(500, 500).ToString(), root_damage_rect.ToString());
  
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_TRUE(GetRenderSurface(child1)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, VerifyDamageForUpdateRects) {
    LayerImpl* root = CreateAndSetUpTestTreeWithOneSurface();
    LayerImpl* child = root->test_properties()->children[0];
  
    // CASE 1: Setting the update rect should cause the corresponding damage to
    //         the surface.
    ClearDamageForAllSurfaces(root);
    child->SetUpdateRect(gfx::Rect(10, 11, 12, 13));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    // Damage position on the surface should be: position of update_rect (10, 11)
    // relative to the child (100, 100).
    gfx::Rect root_damage_rect;
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(gfx::Rect(110, 111, 12, 13).ToString(),
              root_damage_rect.ToString());
  
    // CASE 2: The same update rect twice in a row still produces the same
    //         damage.
    ClearDamageForAllSurfaces(root);
    child->SetUpdateRect(gfx::Rect(10, 11, 12, 13));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(gfx::Rect(110, 111, 12, 13).ToString(),
              root_damage_rect.ToString());
  
    // CASE 3: Setting a different update rect should cause damage on the new
    //         update region, but no additional exposed old region.
    ClearDamageForAllSurfaces(root);
    child->SetUpdateRect(gfx::Rect(20, 25, 1, 2));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    // Damage position on the surface should be: position of update_rect (20, 25)
    // relative to the child (100, 100).
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(gfx::Rect(120, 125, 1, 2).ToString(), root_damage_rect.ToString());
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, VerifyDamageForLayerDamageRects) {
    LayerImpl* root = CreateAndSetUpTestTreeWithOneSurface();
    LayerImpl* child = root->test_properties()->children[0];
  
    // CASE 1: Adding the layer damage rect should cause the corresponding damage
    // to the surface.
    ClearDamageForAllSurfaces(root);
    child->AddDamageRect(gfx::Rect(10, 11, 12, 13));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    // Damage position on the surface should be: position of layer damage_rect
    // (10, 11) relative to the child (100, 100).
    gfx::Rect root_damage_rect;
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(true, root_damage_rect.Contains(gfx::Rect(110, 111, 12, 13)));
  
    // CASE 2: The same layer damage rect twice in a row still produces the same
    // damage.
    ClearDamageForAllSurfaces(root);
    child->AddDamageRect(gfx::Rect(10, 11, 12, 13));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(true, root_damage_rect.Contains(gfx::Rect(110, 111, 12, 13)));
  
    // CASE 3: Adding a different layer damage rect should cause damage on the
    // new damaged region, but no additional exposed old region.
    ClearDamageForAllSurfaces(root);
    child->AddDamageRect(gfx::Rect(20, 25, 1, 2));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    // Damage position on the surface should be: position of layer damage_rect
    // (20, 25) relative to the child (100, 100).
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(true, root_damage_rect.Contains(gfx::Rect(120, 125, 1, 2)));
  
    // CASE 4: Adding multiple layer damage rects should cause a unified
    // damage on root damage rect.
    ClearDamageForAllSurfaces(root);
    child->AddDamageRect(gfx::Rect(20, 25, 1, 2));
    child->AddDamageRect(gfx::Rect(10, 15, 3, 4));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    // Damage position on the surface should be: position of layer damage_rect
    // (20, 25) relative to the child (100, 100).
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(true, root_damage_rect.Contains(gfx::Rect(120, 125, 1, 2)));
    EXPECT_EQ(true, root_damage_rect.Contains(gfx::Rect(110, 115, 3, 4)));
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, VerifyDamageForLayerUpdateAndDamageRects) {
    LayerImpl* root = CreateAndSetUpTestTreeWithOneSurface();
    LayerImpl* child = root->test_properties()->children[0];
  
    // CASE 1: Adding the layer damage rect and update rect should cause the
    // corresponding damage to the surface.
    ClearDamageForAllSurfaces(root);
    child->AddDamageRect(gfx::Rect(5, 6, 12, 13));
    child->SetUpdateRect(gfx::Rect(15, 16, 14, 10));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    // Damage position on the surface should be: position of unified layer
    // damage_rect and update rect (5, 6)
    // relative to the child (100, 100).
    gfx::Rect root_damage_rect;
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(true, root_damage_rect.Contains(gfx::Rect(105, 106, 24, 20)));
  
    // CASE 2: The same layer damage rect and update rect twice in a row still
    // produces the same damage.
    ClearDamageForAllSurfaces(root);
    child->AddDamageRect(gfx::Rect(10, 11, 12, 13));
    child->SetUpdateRect(gfx::Rect(10, 11, 14, 15));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(true, root_damage_rect.Contains(gfx::Rect(110, 111, 14, 15)));
  
    // CASE 3: Adding a different layer damage rect and update rect should cause
    // damage on the new damaged region, but no additional exposed old region.
    ClearDamageForAllSurfaces(root);
    child->AddDamageRect(gfx::Rect(20, 25, 2, 3));
    child->SetUpdateRect(gfx::Rect(5, 10, 7, 8));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    // Damage position on the surface should be: position of unified layer damage
    // rect and update rect (5, 10) relative to the child (100, 100).
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(true, root_damage_rect.Contains(gfx::Rect(105, 110, 17, 18)));
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, VerifyDamageForPropertyChanges) {
    LayerImpl* root = CreateAndSetUpTestTreeWithOneSurface();
    LayerImpl* child = root->test_properties()->children[0];
  
    // CASE 1: The layer's property changed flag takes priority over update rect.
    //
    child->test_properties()->force_render_surface = true;
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    ClearDamageForAllSurfaces(root);
    child->SetUpdateRect(gfx::Rect(10, 11, 12, 13));
    root->layer_tree_impl()->SetOpacityMutated(child->element_id(), 0.5f);
    EmulateDrawingOneFrame(root);
  
    ASSERT_EQ(2, GetRenderSurface(root)->num_contributors());
  
    // Damage should be the entire child layer in target_surface space.
    gfx::Rect expected_rect = gfx::Rect(100, 100, 30, 30);
    gfx::Rect root_damage_rect;
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(expected_rect.ToString(), root_damage_rect.ToString());
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_TRUE(GetRenderSurface(child)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  
    // CASE 2: If a layer moves due to property change, it damages both the new
    //         location and the old (exposed) location. The old location is the
    //         entire old layer, not just the update_rect.
  
    // Cycle one frame of no change, just to sanity check that the next rect is
    // not because of the old damage state.
    ClearDamageForAllSurfaces(root);
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_TRUE(root_damage_rect.IsEmpty());
  
    // Then, test the actual layer movement.
    ClearDamageForAllSurfaces(root);
    gfx::Transform translation;
    translation.Translate(100.f, 130.f);
    root->layer_tree_impl()->SetTransformMutated(child->element_id(),
                                                 translation);
    EmulateDrawingOneFrame(root);
  
    // Expect damage to be the combination of the previous one and the new one.
    expected_rect.Union(gfx::Rect(200, 230, 30, 30));
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_FLOAT_RECT_EQ(expected_rect, root_damage_rect);
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    // Transform from browser animation should not be considered as damage from
    // contributing layer since it is applied to the whole layer which has a
    // render surface.
    EXPECT_FALSE(GetRenderSurface(child)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest,
         VerifyDamageForPropertyChangesFromContributingContents) {
    LayerImpl* root = CreateAndSetUpTestTreeWithTwoSurfaces();
    LayerImpl* child1 = root->test_properties()->children[0];
    LayerImpl* child2 = root->test_properties()->children[1];
    LayerImpl* grandchild1 = child1->test_properties()->children[0];
  
    // CASE 1: The child1's opacity changed.
    ClearDamageForAllSurfaces(root);
    root->layer_tree_impl()->SetOpacityMutated(child1->element_id(), 0.5f);
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_FALSE(GetRenderSurface(child1)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
  
    // CASE 2: The layer2's opacity changed.
    child2->test_properties()->force_render_surface = true;
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    ClearDamageForAllSurfaces(root);
    root->layer_tree_impl()->SetOpacityMutated(child2->element_id(), 0.5f);
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_FALSE(GetRenderSurface(child1)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
  
    // CASE 3: The grandchild1's opacity changed.
    grandchild1->test_properties()->force_render_surface = true;
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    ClearDamageForAllSurfaces(root);
    root->layer_tree_impl()->SetOpacityMutated(grandchild1->element_id(), 0.5f);
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_TRUE(GetRenderSurface(child1)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest,
         VerifyDamageForUpdateAndDamageRectsFromContributingContents) {
    LayerImpl* root = CreateAndSetUpTestTreeWithTwoSurfaces();
    LayerImpl* child1 = root->test_properties()->children[0];
    LayerImpl* child2 = root->test_properties()->children[1];
    LayerImpl* grandchild1 = child1->test_properties()->children[0];
  
    // CASE 1: Adding the layer1's damage rect and update rect should cause the
    // corresponding damage to the surface.
    child1->SetDrawsContent(true);
    ClearDamageForAllSurfaces(root);
    child1->AddDamageRect(gfx::Rect(105, 106, 12, 15));
    child1->SetUpdateRect(gfx::Rect(115, 116, 12, 15));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_TRUE(GetRenderSurface(child1)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  
    // CASE 2: Adding the layer2's damage rect and update rect should cause the
    // corresponding damage to the surface.
    ClearDamageForAllSurfaces(root);
    child2->AddDamageRect(gfx::Rect(11, 11, 12, 15));
    child2->SetUpdateRect(gfx::Rect(12, 12, 12, 15));
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_FALSE(GetRenderSurface(child1)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
  
    // CASE 3: Adding the grandchild1's damage rect and update rect should cause
    // the corresponding damage to the surface.
    ClearDamageForAllSurfaces(root);
    grandchild1->AddDamageRect(gfx::Rect(1, 0, 2, 5));
    grandchild1->SetUpdateRect(gfx::Rect(2, 1, 2, 5));
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_TRUE(GetRenderSurface(child1)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, VerifyDamageWhenSurfaceRemoved) {
    LayerImpl* root = CreateAndSetUpTestTreeWithTwoSurfaces();
    LayerImpl* surface = root->test_properties()->children[0];
    LayerImpl* child = surface->test_properties()->children[0];
    child->SetDrawsContent(true);
    EmulateDrawingOneFrame(root);
    ClearDamageForAllSurfaces(root);
  
    surface->test_properties()->force_render_surface = false;
    child->SetDrawsContent(false);
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    gfx::Rect root_damage_rect;
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(gfx::Rect(290, 290, 16, 18).ToString(),
              root_damage_rect.ToString());
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, VerifyDamageForTransformedLayer) {
    // If a layer is transformed, the damage rect should still enclose the entire
    // transformed layer.
  
    LayerImpl* root = CreateAndSetUpTestTreeWithOneSurface();
    LayerImpl* child = root->test_properties()->children[0];
    child->test_properties()->force_render_surface = true;
  
    gfx::Transform rotation;
    rotation.Rotate(45.0);
  
    ClearDamageForAllSurfaces(root);
    child->test_properties()->transform_origin = gfx::Point3F(
        child->bounds().width() * 0.5f, child->bounds().height() * 0.5f, 0.f);
    child->SetPosition(gfx::PointF(85.f, 85.f));
    child->NoteLayerPropertyChanged();
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    // Sanity check that the layer actually moved to (85, 85), damaging its old
    // location and new location.
    gfx::Rect root_damage_rect;
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(gfx::Rect(85, 85, 45, 45).ToString(), root_damage_rect.ToString());
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    // Layer's layer_property_changed_not_from_property_trees_ should be
    // considered as damage to render surface.
    EXPECT_TRUE(GetRenderSurface(child)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  
    // With the anchor on the layer's center, now we can test the rotation more
    // intuitively, since it applies about the layer's anchor.
    ClearDamageForAllSurfaces(root);
    root->layer_tree_impl()->SetTransformMutated(child->element_id(), rotation);
    EmulateDrawingOneFrame(root);
  
    // Since the child layer is square, rotation by 45 degrees about the center
    // should increase the size of the expected rect by sqrt(2), centered around
    // (100, 100). The old exposed region should be fully contained in the new
    // region.
    float expected_width = 30.f * sqrt(2.f);
    float expected_position = 100.f - 0.5f * expected_width;
    gfx::Rect expected_rect = gfx::ToEnclosingRect(gfx::RectF(
        expected_position, expected_position, expected_width, expected_width));
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(expected_rect.ToString(), root_damage_rect.ToString());
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    // Transform from browser animation should not be considered as damage from
    // contributing layer since it is applied to the whole layer which has a
    // render surface.
    EXPECT_FALSE(GetRenderSurface(child)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, VerifyDamageForPerspectiveClippedLayer) {
    // If a layer has a perspective transform that causes w < 0, then not
    // clipping the layer can cause an invalid damage rect. This test checks that
    // the w < 0 case is tracked properly.
    //
    // The transform is constructed so that if w < 0 clipping is not performed,
    // the incorrect rect will be very small, specifically: position (500.972504,
    // 498.544617) and size 0.056610 x 2.910767.  Instead, the correctly
    // transformed rect should actually be very huge (i.e. in theory, -infinity
    // on the left), and positioned so that the right-most bound rect will be
    // approximately 501 units in root surface space.
    //
  
    LayerImpl* root = CreateAndSetUpTestTreeWithOneSurface();
    LayerImpl* child = root->test_properties()->children[0];
  
    gfx::Transform transform;
    transform.Translate3d(550.0, 500.0, 0.0);
    transform.ApplyPerspectiveDepth(1.0);
    transform.RotateAboutYAxis(45.0);
    transform.Translate3d(-50.0, -50.0, 0.0);
  
    // Set up the child
    child->SetPosition(gfx::PointF(0.f, 0.f));
    child->SetBounds(gfx::Size(100, 100));
    child->test_properties()->transform = transform;
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    // Sanity check that the child layer's bounds would actually get clipped by
    // w < 0, otherwise this test is not actually testing the intended scenario.
    gfx::RectF test_rect(child->position(), gfx::SizeF(child->bounds()));
    bool clipped = false;
    MathUtil::MapQuad(transform, gfx::QuadF(test_rect), &clipped);
    EXPECT_TRUE(clipped);
  
    // Damage the child without moving it.
    child->test_properties()->force_render_surface = true;
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    ClearDamageForAllSurfaces(root);
    root->layer_tree_impl()->SetOpacityMutated(child->element_id(), 0.5f);
    EmulateDrawingOneFrame(root);
  
    // The expected damage should cover the entire root surface (500x500), but we
    // don't care whether the damage rect was clamped or is larger than the
    // surface for this test.
    gfx::Rect root_damage_rect;
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    gfx::Rect damage_we_care_about = gfx::Rect(gfx::Size(500, 500));
    EXPECT_TRUE(root_damage_rect.Contains(damage_we_care_about));
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_FALSE(GetRenderSurface(child)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, VerifyDamageForBlurredSurface) {
    LayerImpl* root = CreateAndSetUpTestTreeWithTwoSurfaces();
    LayerImpl* surface = root->test_properties()->children[0];
    LayerImpl* child = surface->test_properties()->children[0];
  
    FilterOperations filters;
    filters.Append(FilterOperation::CreateBlurFilter(5.f));
  
    // Setting the filter should not damage the conrresponding render surface.
    ClearDamageForAllSurfaces(root);
    surface->test_properties()->filters = filters;
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    EXPECT_FALSE(GetRenderSurface(root)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
    EXPECT_FALSE(GetRenderSurface(surface)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
  
    // Setting the update rect should cause the corresponding damage to the
    // surface, blurred based on the size of the blur filter.
    ClearDamageForAllSurfaces(root);
    child->SetUpdateRect(gfx::Rect(1, 2, 3, 4));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    // Damage position on the surface should be: position of update_rect (1, 2)
    // relative to the child (300, 300), but expanded by the blur outsets
    // (15, since the blur radius is 5).
    gfx::Rect root_damage_rect;
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(gfx::Rect(286, 287, 33, 34), root_damage_rect);
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_TRUE(GetRenderSurface(surface)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, VerifyDamageForImageFilter) {
    LayerImpl* root = CreateAndSetUpTestTreeWithOneSurface();
    LayerImpl* child = root->test_properties()->children[0];
    gfx::Rect root_damage_rect, child_damage_rect;
  
    // Allow us to set damage on child too.
    child->SetDrawsContent(true);
  
    FilterOperations filters;
    filters.Append(
        FilterOperation::CreateReferenceFilter(sk_make_sp<BlurPaintFilter>(
            2, 2, BlurPaintFilter::TileMode::kClampToBlack_TileMode, nullptr)));
  
    // Setting the filter will damage the whole surface.
    child->test_properties()->force_render_surface = true;
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    ClearDamageForAllSurfaces(root);
    child->layer_tree_impl()->SetFilterMutated(child->element_id(), filters);
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_TRUE(GetRenderSurface(child)->damage_tracker()->GetDamageRectIfValid(
        &child_damage_rect));
  
    // gfx::Rect(100, 100, 30, 30), expanded by 6px for the 2px blur filter.
    EXPECT_EQ(gfx::Rect(94, 94, 42, 42), root_damage_rect);
  
    // gfx::Rect(0, 0, 30, 30), expanded by 6px for the 2px blur filter.
    EXPECT_EQ(gfx::Rect(-6, -6, 42, 42), child_damage_rect);
  
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_FALSE(GetRenderSurface(child)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
  
    // CASE 1: Setting the update rect should damage the whole surface (for now)
    ClearDamageForAllSurfaces(root);
    child->SetUpdateRect(gfx::Rect(1, 1));
    EmulateDrawingOneFrame(root);
  
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_TRUE(GetRenderSurface(child)->damage_tracker()->GetDamageRectIfValid(
        &child_damage_rect));
  
    // gfx::Rect(100, 100, 1, 1), expanded by 6px for the 2px blur filter.
    EXPECT_EQ(gfx::Rect(94, 94, 13, 13), root_damage_rect);
  
    // gfx::Rect(0, 0, 1, 1), expanded by 6px for the 2px blur filter.
    EXPECT_EQ(gfx::Rect(-6, -6, 13, 13), child_damage_rect);
  
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_TRUE(GetRenderSurface(child)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  
    // CASE 2: No changes, so should not damage the surface.
    ClearDamageForAllSurfaces(root);
    EmulateDrawingOneFrame(root);
  
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_TRUE(GetRenderSurface(child)->damage_tracker()->GetDamageRectIfValid(
        &child_damage_rect));
  
    // Should not be expanded by the blur filter.
    EXPECT_EQ(gfx::Rect(), root_damage_rect);
    EXPECT_EQ(gfx::Rect(), child_damage_rect);
  
    EXPECT_FALSE(GetRenderSurface(root)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
    EXPECT_FALSE(GetRenderSurface(child)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, VerifyDamageForTransformedImageFilter) {
    LayerImpl* root = CreateAndSetUpTestTreeWithOneSurface();
    LayerImpl* child = root->test_properties()->children[0];
    gfx::Rect root_damage_rect, child_damage_rect;
  
    // Allow us to set damage on child too.
    child->SetDrawsContent(true);
  
    FilterOperations filters;
    filters.Append(
        FilterOperation::CreateReferenceFilter(sk_make_sp<BlurPaintFilter>(
            2, 2, BlurPaintFilter::TileMode::kClampToBlack_TileMode, nullptr)));
  
    // Setting the filter will damage the whole surface.
    gfx::Transform transform;
    transform.RotateAboutYAxis(60);
    ClearDamageForAllSurfaces(root);
    child->test_properties()->force_render_surface = true;
    child->test_properties()->transform = transform;
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    child->layer_tree_impl()->SetFilterMutated(child->element_id(), filters);
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_TRUE(GetRenderSurface(child)->damage_tracker()->GetDamageRectIfValid(
        &child_damage_rect));
  
    // Blur outset is 6px for a 2px blur.
    int blur_outset = 6;
    int rotated_outset_left = blur_outset / 2;
    int expected_rotated_width = (30 + 2 * blur_outset) / 2;
    gfx::Rect expected_root_damage(100 - rotated_outset_left, 100 - blur_outset,
                                   expected_rotated_width, 30 + 2 * blur_outset);
    expected_root_damage.Union(gfx::Rect(100, 100, 30, 30));
    EXPECT_EQ(expected_root_damage, root_damage_rect);
    EXPECT_EQ(gfx::Rect(-blur_outset, -blur_outset, 30 + 2 * blur_outset,
                        30 + 2 * blur_outset),
              child_damage_rect);
  
    // Setting the update rect should damage the whole surface (for now)
    ClearDamageForAllSurfaces(root);
    child->SetUpdateRect(gfx::Rect(30, 30));
    EmulateDrawingOneFrame(root);
  
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_TRUE(GetRenderSurface(child)->damage_tracker()->GetDamageRectIfValid(
        &child_damage_rect));
  
    int expect_width = 30 + 2 * blur_outset;
    int expect_height = 30 + 2 * blur_outset;
    EXPECT_EQ(gfx::Rect(100 - blur_outset / 2, 100 - blur_outset,
                        expect_width / 2, expect_height),
              root_damage_rect);
    EXPECT_EQ(gfx::Rect(-blur_outset, -blur_outset, expect_width, expect_height),
              child_damage_rect);
  }
  
  TEST_F(DamageTrackerTest, VerifyDamageForHighDPIImageFilter) {
    LayerImpl* root = CreateAndSetUpTestTreeWithOneSurface();
    LayerImpl* child = root->test_properties()->children[0];
    gfx::Rect root_damage_rect, child_damage_rect;
  
    // Allow us to set damage on child too.
    child->SetDrawsContent(true);
  
    FilterOperations filters;
    filters.Append(FilterOperation::CreateBlurFilter(3.f));
  
    // Setting the filter will damage the whole surface.
    ClearDamageForAllSurfaces(root);
    child->test_properties()->force_render_surface = true;
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    int device_scale_factor = 2;
    EmulateDrawingOneFrame(root, device_scale_factor);
    child->layer_tree_impl()->SetFilterMutated(child->element_id(), filters);
    EmulateDrawingOneFrame(root, device_scale_factor);
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_TRUE(GetRenderSurface(child)->damage_tracker()->GetDamageRectIfValid(
        &child_damage_rect));
  
    // Blur outset is 9px for a 3px blur, scaled up by DSF.
    int blur_outset = 9 * device_scale_factor;
    gfx::Rect original_rect(100, 100, 100, 100);
    gfx::Rect expected_child_damage_rect(60, 60);
    expected_child_damage_rect.Inset(-blur_outset, -blur_outset);
    gfx::Rect expected_root_damage_rect(child_damage_rect);
    expected_root_damage_rect.Offset(200, 200);
    gfx::Rect expected_total_damage_rect = expected_root_damage_rect;
    expected_total_damage_rect.Union(original_rect);
    EXPECT_EQ(expected_total_damage_rect, root_damage_rect);
    EXPECT_EQ(expected_child_damage_rect, child_damage_rect);
  
    // Setting the update rect should damage only the affected area (original,
    // outset by 3 * blur sigma * DSF).
    ClearDamageForAllSurfaces(root);
    child->SetUpdateRect(gfx::Rect(30, 30));
    EmulateDrawingOneFrame(root, device_scale_factor);
  
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_TRUE(GetRenderSurface(child)->damage_tracker()->GetDamageRectIfValid(
        &child_damage_rect));
  
    EXPECT_EQ(expected_root_damage_rect, root_damage_rect);
    EXPECT_EQ(expected_child_damage_rect, child_damage_rect);
  }
  
  TEST_F(DamageTrackerTest, VerifyDamageForBackgroundBlurredChild) {
    LayerImpl* root = CreateAndSetUpTestTreeWithTwoSurfaces();
    LayerImpl* child1 = root->test_properties()->children[0];
    LayerImpl* child2 = root->test_properties()->children[1];
  
    // Allow us to set damage on child1 too.
    child1->SetDrawsContent(true);
  
    FilterOperations filters;
    filters.Append(FilterOperation::CreateBlurFilter(2.f));
  
    // Setting the filter will damage the whole surface.
    ClearDamageForAllSurfaces(root);
    child1->test_properties()->background_filters = filters;
    child1->NoteLayerPropertyChanged();
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    // CASE 1: Setting the update rect should cause the corresponding damage to
    //         the surface, blurred based on the size of the child's background
    //         blur filter. Note that child1's render surface has a size of
    //         206x208 due to contributions from grand_child1 and grand_child2.
    ClearDamageForAllSurfaces(root);
    root->SetUpdateRect(gfx::Rect(297, 297, 2, 2));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    gfx::Rect root_damage_rect;
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    // Damage position on the surface should be a composition of the damage on
    // the root and on child2.  Damage on the root should be: position of
    // update_rect (297, 297), but expanded by the blur outsets.
    gfx::Rect expected_damage_rect = gfx::Rect(297, 297, 2, 2);
  
    // 6px spread for a 2px blur.
    expected_damage_rect.Inset(-6, -6, -6, -6);
    EXPECT_EQ(expected_damage_rect.ToString(), root_damage_rect.ToString());
  
    // CASE 2: Setting the update rect should cause the corresponding damage to
    //         the surface, blurred based on the size of the child's background
    //         blur filter. Since the damage extends to the right/bottom outside
    //         of the blurred layer, only the left/top should end up expanded.
    ClearDamageForAllSurfaces(root);
    root->SetUpdateRect(gfx::Rect(297, 297, 30, 30));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    // Damage position on the surface should be a composition of the damage on
    // the root and on child2.  Damage on the root should be: position of
    // update_rect (297, 297), but expanded on the left/top by the blur outsets.
    expected_damage_rect = gfx::Rect(297, 297, 30, 30);
  
    // 6px spread for a 2px blur.
    expected_damage_rect.Inset(-6, -6, 0, 0);
    EXPECT_EQ(expected_damage_rect.ToString(), root_damage_rect.ToString());
  
    // CASE 3: Setting this update rect outside the blurred content_bounds of the
    //         blurred child1 will not cause it to be expanded.
    ClearDamageForAllSurfaces(root);
    root->SetUpdateRect(gfx::Rect(30, 30, 2, 2));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    // Damage on the root should be: position of update_rect (30, 30), not
    // expanded.
    expected_damage_rect = gfx::Rect(30, 30, 2, 2);
  
    EXPECT_EQ(expected_damage_rect.ToString(), root_damage_rect.ToString());
  
    // CASE 4: Setting this update rect inside the blurred content_bounds but
    //         outside the original content_bounds of the blurred child1 will
    //         cause it to be expanded.
    ClearDamageForAllSurfaces(root);
    root->SetUpdateRect(gfx::Rect(99, 99, 1, 1));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    // Damage on the root should be: the originally damaged rect (99,99 1x1)
    // plus the rect that can influence with a 2px blur (93,93 13x13) intersected
    // with the surface rect (100,100 206x208). So no additional damage occurs
    // above or to the left, but there is additional damage within the blurred
    // area.
    expected_damage_rect = gfx::Rect(99, 99, 7, 7);
    EXPECT_EQ(expected_damage_rect.ToString(), root_damage_rect.ToString());
  
    // CASE 5: Setting the update rect on child2, which is above child1, will
    // not get blurred by child1, so it does not need to get expanded.
    ClearDamageForAllSurfaces(root);
    child2->SetUpdateRect(gfx::Rect(1, 1));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    // Damage on child2 should be: position of update_rect offset by the child's
    // position (11, 11), and not expanded by anything.
    expected_damage_rect = gfx::Rect(11, 11, 1, 1);
  
    EXPECT_EQ(expected_damage_rect.ToString(), root_damage_rect.ToString());
  
    // CASE 6: Setting the update rect on child1 will also blur the damage, so
    //         that any pixels needed for the blur are redrawn in the current
    //         frame.
    ClearDamageForAllSurfaces(root);
    child1->SetUpdateRect(gfx::Rect(1, 1));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    // Damage on child1 should be: position of update_rect offset by the child's
    // position (100, 100), and expanded by the damage.
  
    // Damage should be (0,0 1x1), offset by the 100,100 offset of child1 in
    // root, and expanded 6px for the 2px blur (i.e., 94,94 13x13), but there
    // should be no damage outside child1 (i.e. none above or to the left of
    // 100,100.
    expected_damage_rect = gfx::Rect(100, 100, 7, 7);
    EXPECT_EQ(expected_damage_rect.ToString(), root_damage_rect.ToString());
  
    // CASE 7: No changes, so should not damage the surface.
    ClearDamageForAllSurfaces(root);
    // We want to make sure that the background filter doesn't cause empty damage
    // to get expanded. We position child1 so that an expansion of the empty rect
    // would have non-empty intersection with child1 in its target space (root
    // space).
    child1->SetPosition(gfx::PointF());
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    gfx::Rect child_damage_rect;
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_TRUE(GetRenderSurface(child1)->damage_tracker()->GetDamageRectIfValid(
        &child_damage_rect));
  
    // Should not be expanded by the blur filter.
    EXPECT_EQ(gfx::Rect(), root_damage_rect);
    EXPECT_EQ(gfx::Rect(), child_damage_rect);
  }
  
  TEST_F(DamageTrackerTest, VerifyDamageForAddingAndRemovingLayer) {
    LayerImpl* root = CreateAndSetUpTestTreeWithOneSurface();
    LayerImpl* child1 = root->test_properties()->children[0];
  
    // CASE 1: Adding a new layer should cause the appropriate damage.
    //
    ClearDamageForAllSurfaces(root);
    {
      std::unique_ptr<LayerImpl> child2 =
          LayerImpl::Create(host_impl_.active_tree(), 3);
      child2->SetPosition(gfx::PointF(400.f, 380.f));
      child2->SetBounds(gfx::Size(6, 8));
      child2->SetDrawsContent(true);
      root->test_properties()->AddChild(std::move(child2));
    }
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    // Sanity check - all 3 layers should be on the same render surface; render
    // surfaces are tested elsewhere.
    ASSERT_EQ(3, GetRenderSurface(root)->num_contributors());
  
    gfx::Rect root_damage_rect;
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(gfx::Rect(400, 380, 6, 8).ToString(), root_damage_rect.ToString());
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  
    // CASE 2: If the layer is removed, its entire old layer becomes exposed, not
    //         just the last update rect.
  
    // Advance one frame without damage so that we know the damage rect is not
    // leftover from the previous case.
    ClearDamageForAllSurfaces(root);
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_TRUE(root_damage_rect.IsEmpty());
  
    // Then, test removing child1.
    root->test_properties()->RemoveChild(child1);
    child1 = nullptr;
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(gfx::Rect(100, 100, 30, 30).ToString(),
              root_damage_rect.ToString());
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, VerifyDamageForNewUnchangedLayer) {
    // If child2 is added to the layer tree, but it doesn't have any explicit
    // damage of its own, it should still indeed damage the target surface.
  
    LayerImpl* root = CreateAndSetUpTestTreeWithOneSurface();
  
    ClearDamageForAllSurfaces(root);
    {
      std::unique_ptr<LayerImpl> child2 =
          LayerImpl::Create(host_impl_.active_tree(), 3);
      child2->SetPosition(gfx::PointF(400.f, 380.f));
      child2->SetBounds(gfx::Size(6, 8));
      child2->SetDrawsContent(true);
      root->test_properties()->AddChild(std::move(child2));
      root->layer_tree_impl()->BuildLayerListForTesting();
      host_impl_.active_tree()->ResetAllChangeTracking();
      LayerImpl* child2_ptr = host_impl_.active_tree()->LayerById(3);
      // Sanity check the initial conditions of the test, if these asserts
      // trigger, it means the test no longer actually covers the intended
      // scenario.
      ASSERT_FALSE(child2_ptr->LayerPropertyChanged());
      ASSERT_TRUE(child2_ptr->update_rect().IsEmpty());
    }
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    // Sanity check - all 3 layers should be on the same render surface; render
    // surfaces are tested elsewhere.
    ASSERT_EQ(3, GetRenderSurface(root)->num_contributors());
  
    gfx::Rect root_damage_rect;
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(gfx::Rect(400, 380, 6, 8).ToString(), root_damage_rect.ToString());
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, VerifyDamageForMultipleLayers) {
    LayerImpl* root = CreateAndSetUpTestTreeWithOneSurface();
    LayerImpl* child1 = root->test_properties()->children[0];
  
    // In this test we don't want the above tree manipulation to be considered
    // part of the same frame.
    ClearDamageForAllSurfaces(root);
    {
      std::unique_ptr<LayerImpl> child2 =
          LayerImpl::Create(host_impl_.active_tree(), 3);
      child2->SetPosition(gfx::PointF(400.f, 380.f));
      child2->SetBounds(gfx::Size(6, 8));
      child2->SetDrawsContent(true);
      root->test_properties()->AddChild(std::move(child2));
    }
    LayerImpl* child2 = root->test_properties()->children[1];
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    // Damaging two layers simultaneously should cause combined damage.
    // - child1 update rect in surface space: gfx::Rect(100, 100, 1, 2);
    // - child2 update rect in surface space: gfx::Rect(400, 380, 3, 4);
    ClearDamageForAllSurfaces(root);
    child1->SetUpdateRect(gfx::Rect(1, 2));
    child2->SetUpdateRect(gfx::Rect(3, 4));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    gfx::Rect root_damage_rect;
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(gfx::Rect(100, 100, 303, 284).ToString(),
              root_damage_rect.ToString());
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, VerifyDamageForNestedSurfaces) {
    LayerImpl* root = CreateAndSetUpTestTreeWithTwoSurfaces();
    LayerImpl* child1 = root->test_properties()->children[0];
    LayerImpl* child2 = root->test_properties()->children[1];
    LayerImpl* grand_child1 =
        root->test_properties()->children[0]->test_properties()->children[0];
    child2->test_properties()->force_render_surface = true;
    grand_child1->test_properties()->force_render_surface = true;
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    gfx::Rect child_damage_rect;
    gfx::Rect root_damage_rect;
  
    // CASE 1: Damage to a descendant surface should propagate properly to
    //         ancestor surface.
    ClearDamageForAllSurfaces(root);
    root->layer_tree_impl()->SetOpacityMutated(grand_child1->element_id(), 0.5f);
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(child1)->damage_tracker()->GetDamageRectIfValid(
        &child_damage_rect));
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(gfx::Rect(200, 200, 6, 8).ToString(), child_damage_rect.ToString());
    EXPECT_EQ(gfx::Rect(300, 300, 6, 8).ToString(), root_damage_rect.ToString());
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_TRUE(GetRenderSurface(child1)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_FALSE(GetRenderSurface(child2)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
    EXPECT_FALSE(GetRenderSurface(grand_child1)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
  
    // CASE 2: Same as previous case, but with additional damage elsewhere that
    //         should be properly unioned.
    // - child1 surface damage in root surface space:
    //   gfx::Rect(300, 300, 6, 8);
    // - child2 damage in root surface space:
    //   gfx::Rect(11, 11, 18, 18);
    ClearDamageForAllSurfaces(root);
    root->layer_tree_impl()->SetOpacityMutated(grand_child1->element_id(), 0.7f);
    root->layer_tree_impl()->SetOpacityMutated(child2->element_id(), 0.7f);
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(child1)->damage_tracker()->GetDamageRectIfValid(
        &child_damage_rect));
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(gfx::Rect(200, 200, 6, 8).ToString(), child_damage_rect.ToString());
    EXPECT_EQ(gfx::Rect(11, 11, 295, 297).ToString(),
              root_damage_rect.ToString());
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_TRUE(GetRenderSurface(child1)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_FALSE(GetRenderSurface(child2)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
    EXPECT_FALSE(GetRenderSurface(grand_child1)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, VerifyDamageForSurfaceChangeFromDescendantLayer) {
    // If descendant layer changes and affects the content bounds of the render
    // surface, then the entire descendant surface should be damaged, and it
    // should damage its ancestor surface with the old and new surface regions.
  
    // This is a tricky case, since only the first grand_child changes, but the
    // entire surface should be marked dirty.
  
    LayerImpl* root = CreateAndSetUpTestTreeWithTwoSurfaces();
    LayerImpl* child1 = root->test_properties()->children[0];
    LayerImpl* grand_child1 =
        root->test_properties()->children[0]->test_properties()->children[0];
    gfx::Rect child_damage_rect;
    gfx::Rect root_damage_rect;
  
    ClearDamageForAllSurfaces(root);
    grand_child1->SetPosition(gfx::PointF(195.f, 205.f));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(child1)->damage_tracker()->GetDamageRectIfValid(
        &child_damage_rect));
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
  
    // The new surface bounds should be damaged entirely, even though only one of
    // the layers changed.
    EXPECT_EQ(gfx::Rect(190, 190, 11, 23).ToString(),
              child_damage_rect.ToString());
  
    // Damage to the root surface should be the union of child1's *entire* render
    // surface (in target space), and its old exposed area (also in target
    // space).
    EXPECT_EQ(gfx::Rect(290, 290, 16, 23).ToString(),
              root_damage_rect.ToString());
  
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_TRUE(GetRenderSurface(child1)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, VerifyDamageForSurfaceChangeFromAncestorLayer) {
    // An ancestor/owning layer changes that affects the position/transform of
    // the render surface. Note that in this case, the layer_property_changed flag
    // already propagates to the subtree (tested in LayerImpltest), which damages
    // the entire child1 surface, but the damage tracker still needs the correct
    // logic to compute the exposed region on the root surface.
  
    // TODO(shawnsingh): the expectations of this test case should change when we
    // add support for a unique scissor_rect per RenderSurface. In that case, the
    // child1 surface should be completely unchanged, since we are only
    // transforming it, while the root surface would be damaged appropriately.
  
    LayerImpl* root = CreateAndSetUpTestTreeWithTwoSurfaces();
    LayerImpl* child1 = root->test_properties()->children[0];
    gfx::Rect child_damage_rect;
    gfx::Rect root_damage_rect;
  
    ClearDamageForAllSurfaces(root);
    gfx::Transform translation;
    translation.Translate(-50.f, -50.f);
    root->layer_tree_impl()->SetTransformMutated(child1->element_id(),
                                                 translation);
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(child1)->damage_tracker()->GetDamageRectIfValid(
        &child_damage_rect));
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
  
    // The new surface bounds should be damaged entirely.
    EXPECT_EQ(gfx::Rect(190, 190, 16, 18).ToString(),
              child_damage_rect.ToString());
  
    // The entire child1 surface and the old exposed child1 surface should damage
    // the root surface.
    //  - old child1 surface in target space: gfx::Rect(290, 290, 16, 18)
    //  - new child1 surface in target space: gfx::Rect(240, 240, 16, 18)
    EXPECT_EQ(gfx::Rect(240, 240, 66, 68).ToString(),
              root_damage_rect.ToString());
  
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_FALSE(GetRenderSurface(child1)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, VerifyDamageForAddingAndRemovingRenderSurfaces) {
    LayerImpl* root = CreateAndSetUpTestTreeWithTwoSurfaces();
    LayerImpl* child1 = root->test_properties()->children[0];
    gfx::Rect child_damage_rect;
    gfx::Rect root_damage_rect;
  
    // CASE 1: If a descendant surface disappears, its entire old area becomes
    //         exposed.
    ClearDamageForAllSurfaces(root);
    child1->test_properties()->force_render_surface = false;
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    // Sanity check that there is only one surface now.
    ASSERT_EQ(GetRenderSurface(child1), GetRenderSurface(root));
    ASSERT_EQ(4, GetRenderSurface(root)->num_contributors());
  
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(gfx::Rect(290, 290, 16, 18).ToString(),
              root_damage_rect.ToString());
  
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  
    // CASE 2: If a descendant surface appears, its entire old area becomes
    //         exposed.
  
    // Cycle one frame of no change, just to sanity check that the next rect is
    // not because of the old damage state.
    ClearDamageForAllSurfaces(root);
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_TRUE(root_damage_rect.IsEmpty());
  
    // Then change the tree so that the render surface is added back.
    ClearDamageForAllSurfaces(root);
    child1->test_properties()->force_render_surface = true;
  
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    // Sanity check that there is a new surface now.
    ASSERT_TRUE(GetRenderSurface(child1));
    EXPECT_EQ(3, GetRenderSurface(root)->num_contributors());
    EXPECT_EQ(2, GetRenderSurface(child1)->num_contributors());
  
    EXPECT_TRUE(GetRenderSurface(child1)->damage_tracker()->GetDamageRectIfValid(
        &child_damage_rect));
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(gfx::Rect(190, 190, 16, 18).ToString(),
              child_damage_rect.ToString());
    EXPECT_EQ(gfx::Rect(290, 290, 16, 18).ToString(),
              root_damage_rect.ToString());
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, VerifyNoDamageWhenNothingChanged) {
    LayerImpl* root = CreateAndSetUpTestTreeWithTwoSurfaces();
    LayerImpl* child1 = root->test_properties()->children[0];
    gfx::Rect child_damage_rect;
    gfx::Rect root_damage_rect;
  
    // CASE 1: If nothing changes, the damage rect should be empty.
    //
    ClearDamageForAllSurfaces(root);
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(child1)->damage_tracker()->GetDamageRectIfValid(
        &child_damage_rect));
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_TRUE(child_damage_rect.IsEmpty());
    EXPECT_TRUE(root_damage_rect.IsEmpty());
    EXPECT_FALSE(GetRenderSurface(root)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
  
    // CASE 2: If nothing changes twice in a row, the damage rect should still be
    //         empty.
    //
    ClearDamageForAllSurfaces(root);
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(child1)->damage_tracker()->GetDamageRectIfValid(
        &child_damage_rect));
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_TRUE(child_damage_rect.IsEmpty());
    EXPECT_TRUE(root_damage_rect.IsEmpty());
    EXPECT_FALSE(GetRenderSurface(root)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, VerifyNoDamageForUpdateRectThatDoesNotDrawContent) {
    LayerImpl* root = CreateAndSetUpTestTreeWithTwoSurfaces();
    LayerImpl* child1 = root->test_properties()->children[0];
    gfx::Rect child_damage_rect;
    gfx::Rect root_damage_rect;
  
    // In our specific tree, the update rect of child1 should not cause any
    // damage to any surface because it does not actually draw content.
    ClearDamageForAllSurfaces(root);
    child1->SetUpdateRect(gfx::Rect(1, 2));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(child1)->damage_tracker()->GetDamageRectIfValid(
        &child_damage_rect));
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_TRUE(child_damage_rect.IsEmpty());
    EXPECT_TRUE(root_damage_rect.IsEmpty());
    EXPECT_FALSE(GetRenderSurface(root)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, VerifyDamageForMask) {
    LayerImpl* root = CreateAndSetUpTestTreeWithOneSurface();
    LayerImpl* child = root->test_properties()->children[0];
  
    // In the current implementation of the damage tracker, changes to mask
    // layers should damage the entire corresponding surface.
  
    ClearDamageForAllSurfaces(root);
  
    // Set up the mask layer.
    {
      std::unique_ptr<LayerImpl> mask_layer =
          LayerImpl::Create(host_impl_.active_tree(), 3);
      mask_layer->SetPosition(child->position());
      mask_layer->SetBounds(child->bounds());
      child->test_properties()->SetMaskLayer(std::move(mask_layer));
      child->test_properties()->force_render_surface = true;
    }
    LayerImpl* mask_layer = child->test_properties()->mask_layer;
  
    // Add opacity and a grand_child so that the render surface persists even
    // after we remove the mask.
    {
      std::unique_ptr<LayerImpl> grand_child =
          LayerImpl::Create(host_impl_.active_tree(), 4);
      grand_child->SetPosition(gfx::PointF(2.f, 2.f));
      grand_child->SetBounds(gfx::Size(2, 2));
      grand_child->SetDrawsContent(true);
      child->test_properties()->AddChild(std::move(grand_child));
    }
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    // CASE 1: the update_rect on a mask layer should damage the entire target
    //         surface.
    ClearDamageForAllSurfaces(root);
    mask_layer->SetUpdateRect(gfx::Rect(1, 2, 3, 4));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    gfx::Rect child_damage_rect;
    EXPECT_TRUE(GetRenderSurface(child)->damage_tracker()->GetDamageRectIfValid(
        &child_damage_rect));
    EXPECT_EQ(gfx::Rect(30, 30).ToString(), child_damage_rect.ToString());
  
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_FALSE(GetRenderSurface(child)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
  
    // CASE 2: a property change on the mask layer should damage the entire
    //         target surface.
  
    // Advance one frame without damage so that we know the damage rect is not
    // leftover from the previous case.
    ClearDamageForAllSurfaces(root);
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(child)->damage_tracker()->GetDamageRectIfValid(
        &child_damage_rect));
    EXPECT_TRUE(child_damage_rect.IsEmpty());
  
    // Then test the property change.
    ClearDamageForAllSurfaces(root);
    mask_layer->NoteLayerPropertyChanged();
  
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(child)->damage_tracker()->GetDamageRectIfValid(
        &child_damage_rect));
    EXPECT_EQ(gfx::Rect(30, 30).ToString(), child_damage_rect.ToString());
  
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_FALSE(GetRenderSurface(child)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
  
    // CASE 3: removing the mask also damages the entire target surface.
    //
  
    // Advance one frame without damage so that we know the damage rect is not
    // leftover from the previous case.
    ClearDamageForAllSurfaces(root);
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(child)->damage_tracker()->GetDamageRectIfValid(
        &child_damage_rect));
    EXPECT_TRUE(child_damage_rect.IsEmpty());
  
    // Then test mask removal.
    ClearDamageForAllSurfaces(root);
    child->test_properties()->SetMaskLayer(nullptr);
    child->NoteLayerPropertyChanged();
    ASSERT_TRUE(child->LayerPropertyChanged());
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    // Sanity check that a render surface still exists.
    ASSERT_TRUE(GetRenderSurface(child));
  
    EXPECT_TRUE(GetRenderSurface(child)->damage_tracker()->GetDamageRectIfValid(
        &child_damage_rect));
    EXPECT_EQ(gfx::Rect(30, 30).ToString(), child_damage_rect.ToString());
  
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, DamageWhenAddedExternally) {
    LayerImpl* root = CreateAndSetUpTestTreeWithOneSurface();
    LayerImpl* child = root->test_properties()->children[0];
  
    // Case 1: This test ensures that when the tracker is given damage, that
    //         it is included with any other partial damage.
    //
    ClearDamageForAllSurfaces(root);
    child->SetUpdateRect(gfx::Rect(10, 11, 12, 13));
    GetRenderSurface(root)->damage_tracker()->AddDamageNextUpdate(
        gfx::Rect(15, 16, 32, 33));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    gfx::Rect root_damage_rect;
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(gfx::UnionRects(gfx::Rect(15, 16, 32, 33),
                              gfx::Rect(100 + 10, 100 + 11, 12, 13)).ToString(),
              root_damage_rect.ToString());
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  
    // Case 2: An additional sanity check that adding damage works even when
    //         nothing on the layer tree changed.
    //
    ClearDamageForAllSurfaces(root);
    GetRenderSurface(root)->damage_tracker()->AddDamageNextUpdate(
        gfx::Rect(30, 31, 14, 15));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(gfx::Rect(30, 31, 14, 15).ToString(), root_damage_rect.ToString());
    EXPECT_FALSE(GetRenderSurface(root)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, VerifyDamageWithNoContributingLayers) {
    std::unique_ptr<LayerImpl> root =
        LayerImpl::Create(host_impl_.active_tree(), 1);
    root->test_properties()->force_render_surface = true;
    host_impl_.active_tree()->SetRootLayerForTesting(std::move(root));
    LayerImpl* root_ptr = host_impl_.active_tree()->root_layer_for_testing();
    root_ptr->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root_ptr);
  
    DCHECK_EQ(GetRenderSurface(root_ptr), root_ptr->render_target());
    RenderSurfaceImpl* target_surface = GetRenderSurface(root_ptr);
    gfx::Rect damage_rect;
    EXPECT_TRUE(
        target_surface->damage_tracker()->GetDamageRectIfValid(&damage_rect));
    EXPECT_TRUE(damage_rect.IsEmpty());
    EXPECT_FALSE(GetRenderSurface(root_ptr)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, VerifyDamageAccumulatesUntilReset) {
    // If damage is not cleared, it should accumulate.
  
    LayerImpl* root = CreateAndSetUpTestTreeWithOneSurface();
    LayerImpl* child = root->test_properties()->children[0];
  
    ClearDamageForAllSurfaces(root);
    child->SetUpdateRect(gfx::Rect(10.f, 11.f, 1.f, 2.f));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
  
    // Sanity check damage after the first frame; this isnt the actual test yet.
    gfx::Rect root_damage_rect;
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(gfx::Rect(110, 111, 1, 2).ToString(), root_damage_rect.ToString());
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  
    // New damage, without having cleared the previous damage, should be unioned
    // to the previous one.
    child->SetUpdateRect(gfx::Rect(20, 25, 1, 2));
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_EQ(gfx::Rect(110, 111, 11, 16).ToString(),
              root_damage_rect.ToString());
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  
    // If we notify the damage tracker that we drew the damaged area, then damage
    // should be emptied.
    GetRenderSurface(root)->damage_tracker()->DidDrawDamagedArea();
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_TRUE(root_damage_rect.IsEmpty());
    EXPECT_FALSE(GetRenderSurface(root)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
  
    // Damage should remain empty even after one frame, since there's yet no new
    // damage.
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    EmulateDrawingOneFrame(root);
    EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &root_damage_rect));
    EXPECT_TRUE(root_damage_rect.IsEmpty());
    EXPECT_FALSE(GetRenderSurface(root)
                     ->damage_tracker()
                     ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, HugeDamageRect) {
    // This number is so large that we start losting floating point accuracy.
    const int kBigNumber = 900000000;
    // Walk over a range to find floating point inaccuracy boundaries that move
    // toward the wrong direction.
    const int kRange = 5000;
  
    for (int i = 0; i < kRange; ++i) {
      LayerImpl* root = CreateAndSetUpTestTreeWithOneSurface();
      LayerImpl* child = root->test_properties()->children[0];
  
      gfx::Transform transform;
      transform.Translate(-kBigNumber, -kBigNumber);
  
      // The child layer covers (0, 0, i, i) of the viewport,
      // but has a huge negative position.
      child->SetPosition(gfx::PointF());
      child->SetBounds(gfx::Size(kBigNumber + i, kBigNumber + i));
      child->test_properties()->transform = transform;
      root->layer_tree_impl()->property_trees()->needs_rebuild = true;
      float device_scale_factor = 1.f;
      // Visible rects computed from combining clips in target space and root
      // space don't match because of the loss in floating point accuracy. So, we
      // skip verify_clip_tree_calculations.
      EmulateDrawingOneFrame(root, device_scale_factor);
  
      // The expected damage should cover the visible part of the child layer,
      // which is (0, 0, i, i) in the viewport.
      gfx::Rect root_damage_rect;
      EXPECT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
          &root_damage_rect));
      gfx::Rect damage_we_care_about = gfx::Rect(i, i);
      EXPECT_LE(damage_we_care_about.right(), root_damage_rect.right());
      EXPECT_LE(damage_we_care_about.bottom(), root_damage_rect.bottom());
      EXPECT_TRUE(GetRenderSurface(root)
                      ->damage_tracker()
                      ->has_damage_from_contributing_content());
    }
  }
  
  TEST_F(DamageTrackerTest, DamageRectTooBig) {
    LayerImpl* root = CreateAndSetUpTestTreeWithOneSurface(2);
    LayerImpl* child1 = root->test_properties()->children[0];
    LayerImpl* child2 = root->test_properties()->children[1];
  
    // Really far left.
    child1->SetPosition(gfx::PointF(std::numeric_limits<int>::min() + 100, 0));
    child1->SetBounds(gfx::Size(1, 1));
  
    // Really far right.
    child2->SetPosition(gfx::PointF(std::numeric_limits<int>::max() - 100, 0));
    child2->SetBounds(gfx::Size(1, 1));
  
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    float device_scale_factor = 1.f;
    EmulateDrawingOneFrame(root, device_scale_factor);
  
    // The expected damage would be too large to store in a gfx::Rect, so we
    // should damage everything (ie, we don't have a valid rect).
    gfx::Rect damage_rect;
    EXPECT_FALSE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &damage_rect));
    EXPECT_EQ(GetRenderSurface(root)->content_rect(),
              GetRenderSurface(root)->GetDamageRect());
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, DamageRectTooBigWithFilter) {
    LayerImpl* root = CreateAndSetUpTestTreeWithOneSurface(2);
    LayerImpl* child1 = root->test_properties()->children[0];
    LayerImpl* child2 = root->test_properties()->children[1];
  
    FilterOperations filters;
    filters.Append(FilterOperation::CreateBlurFilter(5.f));
    root->SetDrawsContent(true);
    root->test_properties()->background_filters = filters;
  
    // Really far left.
    child1->SetPosition(gfx::PointF(std::numeric_limits<int>::min() + 100, 0));
    child1->SetBounds(gfx::Size(1, 1));
  
    // Really far right.
    child2->SetPosition(gfx::PointF(std::numeric_limits<int>::max() - 100, 0));
    child2->SetBounds(gfx::Size(1, 1));
  
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    float device_scale_factor = 1.f;
    EmulateDrawingOneFrame(root, device_scale_factor);
  
    // The expected damage would be too large to store in a gfx::Rect, so we
    // should damage everything (ie, we don't have a valid rect).
    gfx::Rect damage_rect;
    EXPECT_FALSE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &damage_rect));
    EXPECT_EQ(GetRenderSurface(root)->content_rect(),
              GetRenderSurface(root)->GetDamageRect());
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, DamageRectTooBigInRenderSurface) {
    LayerImpl* root = CreateAndSetUpTestTreeWithTwoSurfaces();
    LayerImpl* child1 = root->test_properties()->children[0];
    LayerImpl* grandchild1 = child1->test_properties()->children[0];
    LayerImpl* grandchild2 = child1->test_properties()->children[1];
  
    // Really far left.
    grandchild1->SetPosition(
        gfx::PointF(std::numeric_limits<int>::min() + 500, 0));
    grandchild1->SetBounds(gfx::Size(1, 1));
    grandchild1->SetDrawsContent(true);
  
    // Really far right.
    grandchild2->SetPosition(
        gfx::PointF(std::numeric_limits<int>::max() - 500, 0));
    grandchild2->SetBounds(gfx::Size(1, 1));
    grandchild2->SetDrawsContent(true);
  
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    float device_scale_factor = 1.f;
    RenderSurfaceList render_surface_list;
    ExecuteCalculateDrawProperties(root, device_scale_factor,
                                   &render_surface_list);
    // Avoid the descendant-only property change path that skips unioning damage
    // from descendant layers.
    GetRenderSurface(child1)->NoteAncestorPropertyChanged();
    DamageTracker::UpdateDamageTracking(host_impl_.active_tree(),
                                        render_surface_list);
  
    // The expected damage would be too large to store in a gfx::Rect, so we
    // should damage everything on child1.
    gfx::Rect damage_rect;
    EXPECT_FALSE(GetRenderSurface(child1)->damage_tracker()->GetDamageRectIfValid(
        &damage_rect));
    EXPECT_EQ(GetRenderSurface(child1)->content_rect(),
              GetRenderSurface(child1)->GetDamageRect());
  
    // However, the root should just use the child1 render surface's content rect
    // as damage.
    ASSERT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &damage_rect));
    EXPECT_TRUE(damage_rect.Contains(GetRenderSurface(root)->content_rect()));
    EXPECT_TRUE(damage_rect.Contains(
        gfx::ToEnclosingRect(GetRenderSurface(child1)->DrawableContentRect())));
    EXPECT_EQ(damage_rect, GetRenderSurface(root)->GetDamageRect());
  
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_TRUE(GetRenderSurface(child1)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  
    // Add new damage, without changing properties, which goes down a different
    // path in the damage tracker.
    root->layer_tree_impl()->ResetAllChangeTracking();
    grandchild1->AddDamageRect(gfx::Rect(grandchild1->bounds()));
    grandchild2->AddDamageRect(gfx::Rect(grandchild1->bounds()));
  
    // Recompute all damage / properties.
    render_surface_list.clear();
    ExecuteCalculateDrawProperties(root, device_scale_factor,
                                   &render_surface_list);
    DamageTracker::UpdateDamageTracking(host_impl_.active_tree(),
                                        render_surface_list);
  
    // Child1 should still not have a valid rect, since the union of the damage of
    // its children is not representable by a single rect.
    EXPECT_FALSE(GetRenderSurface(child1)->damage_tracker()->GetDamageRectIfValid(
        &damage_rect));
    EXPECT_EQ(GetRenderSurface(child1)->content_rect(),
              GetRenderSurface(child1)->GetDamageRect());
  
    // Root should have valid damage and contain both its content rect and the
    // drawable content rect of child1.
    ASSERT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &damage_rect));
    EXPECT_TRUE(damage_rect.Contains(GetRenderSurface(root)->content_rect()));
    EXPECT_TRUE(damage_rect.Contains(
        gfx::ToEnclosingRect(GetRenderSurface(child1)->DrawableContentRect())));
    EXPECT_EQ(damage_rect, GetRenderSurface(root)->GetDamageRect());
  
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_TRUE(GetRenderSurface(child1)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  }
  
  TEST_F(DamageTrackerTest, DamageRectTooBigInRenderSurfaceWithFilter) {
    LayerImpl* root = CreateAndSetUpTestTreeWithTwoSurfaces();
    LayerImpl* child1 = root->test_properties()->children[0];
    LayerImpl* grandchild1 = child1->test_properties()->children[0];
    LayerImpl* grandchild2 = child1->test_properties()->children[1];
  
    // Set up a moving pixels filter on the child.
    FilterOperations filters;
    filters.Append(FilterOperation::CreateBlurFilter(5.f));
    child1->SetDrawsContent(true);
    child1->test_properties()->background_filters = filters;
  
    // Really far left.
    grandchild1->SetPosition(
        gfx::PointF(std::numeric_limits<int>::min() + 500, 0));
    grandchild1->SetBounds(gfx::Size(1, 1));
    grandchild1->SetDrawsContent(true);
  
    // Really far right.
    grandchild2->SetPosition(
        gfx::PointF(std::numeric_limits<int>::max() - 500, 0));
    grandchild2->SetBounds(gfx::Size(1, 1));
    grandchild2->SetDrawsContent(true);
  
    root->layer_tree_impl()->property_trees()->needs_rebuild = true;
    float device_scale_factor = 1.f;
    RenderSurfaceList render_surface_list;
    ExecuteCalculateDrawProperties(root, device_scale_factor,
                                   &render_surface_list);
    // Avoid the descendant-only property change path that skips unioning damage
    // from descendant layers.
    GetRenderSurface(child1)->NoteAncestorPropertyChanged();
    DamageTracker::UpdateDamageTracking(host_impl_.active_tree(),
                                        render_surface_list);
  
    // The expected damage would be too large to store in a gfx::Rect, so we
    // should damage everything on child1.
    gfx::Rect damage_rect;
    EXPECT_FALSE(GetRenderSurface(child1)->damage_tracker()->GetDamageRectIfValid(
        &damage_rect));
    EXPECT_EQ(GetRenderSurface(child1)->content_rect(),
              GetRenderSurface(child1)->GetDamageRect());
  
    // However, the root should just use the child1 render surface's content rect
    // as damage.
    ASSERT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &damage_rect));
    EXPECT_TRUE(damage_rect.Contains(GetRenderSurface(root)->content_rect()));
    EXPECT_TRUE(damage_rect.Contains(
        gfx::ToEnclosingRect(GetRenderSurface(child1)->DrawableContentRect())));
    EXPECT_EQ(damage_rect, GetRenderSurface(root)->GetDamageRect());
  
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_TRUE(GetRenderSurface(child1)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  
    // Add new damage, without changing properties, which goes down a different
    // path in the damage tracker.
    root->layer_tree_impl()->ResetAllChangeTracking();
    grandchild1->AddDamageRect(gfx::Rect(grandchild1->bounds()));
    grandchild2->AddDamageRect(gfx::Rect(grandchild1->bounds()));
  
    // Recompute all damage / properties.
    render_surface_list.clear();
    ExecuteCalculateDrawProperties(root, device_scale_factor,
                                   &render_surface_list);
    DamageTracker::UpdateDamageTracking(host_impl_.active_tree(),
                                        render_surface_list);
  
    // Child1 should still not have a valid rect, since the union of the damage of
    // its children is not representable by a single rect.
    EXPECT_FALSE(GetRenderSurface(child1)->damage_tracker()->GetDamageRectIfValid(
        &damage_rect));
    EXPECT_EQ(GetRenderSurface(child1)->content_rect(),
              GetRenderSurface(child1)->GetDamageRect());
  
    // Root should have valid damage and contain both its content rect and the
    // drawable content rect of child1.
    ASSERT_TRUE(GetRenderSurface(root)->damage_tracker()->GetDamageRectIfValid(
        &damage_rect));
    EXPECT_TRUE(damage_rect.Contains(GetRenderSurface(root)->content_rect()));
    EXPECT_TRUE(damage_rect.Contains(
        gfx::ToEnclosingRect(GetRenderSurface(child1)->DrawableContentRect())));
    EXPECT_EQ(damage_rect, GetRenderSurface(root)->GetDamageRect());
  
    EXPECT_TRUE(GetRenderSurface(root)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
    EXPECT_TRUE(GetRenderSurface(child1)
                    ->damage_tracker()
                    ->has_damage_from_contributing_content());
  }
  
  }  // namespace
  }  // namespace cc
  