text: // Copyright (c) 2012 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 "chrome/browser/gpu/gpu_feature_checker.h"
  
  #include "base/logging.h"
  #include "content/public/browser/browser_thread.h"
  #include "content/public/browser/gpu_data_manager.h"
  
  namespace {
  
  // A false return value is always valid, but a true one is only valid if full
  // GPU info has been collected in a GPU process.
  bool IsFeatureAllowed(content::GpuDataManager* manager,
                        gpu::GpuFeatureType feature) {
    return (manager->GpuAccessAllowed(NULL) &&
            !manager->IsFeatureBlacklisted(feature));
  }
  
  }  // namespace
  
  GPUFeatureChecker::GPUFeatureChecker(gpu::GpuFeatureType feature,
                                       FeatureAvailableCallback callback)
      : feature_(feature),
        callback_(callback) {
  }
  
  GPUFeatureChecker::~GPUFeatureChecker() {
  }
  
  void GPUFeatureChecker::CheckGPUFeatureAvailability() {
    CHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
  
    bool finalized = true;
  #if defined(OS_LINUX)
    // On Windows and Mac, so far we can always make the final WebGL blacklisting
    // decision based on partial GPU info; on Linux, we need to launch the GPU
    // process to collect full GPU info and make the final decision.
    finalized = false;
  #endif
  
    content::GpuDataManager* manager = content::GpuDataManager::GetInstance();
    if (manager->IsCompleteGpuInfoAvailable())
      finalized = true;
  
    bool feature_allowed = IsFeatureAllowed(manager, feature_);
    if (!feature_allowed)
      finalized = true;
  
    if (finalized) {
      callback_.Run(feature_allowed);
    } else {
      // Matched with a Release in OnGpuInfoUpdate.
      AddRef();
  
      manager->AddObserver(this);
      manager->RequestCompleteGpuInfoIfNeeded();
    }
  }
  
  void GPUFeatureChecker::OnGpuInfoUpdate() {
    content::GpuDataManager* manager = content::GpuDataManager::GetInstance();
    manager->RemoveObserver(this);
    bool feature_allowed = IsFeatureAllowed(manager, feature_);
    callback_.Run(feature_allowed);
  
    // Matches the AddRef in HasFeature().
    Release();
  }
  