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.
  
  #ifndef CONTENT_BROWSER_GAMEPAD_GAMEPAD_SERVICE_H_
  #define CONTENT_BROWSER_GAMEPAD_GAMEPAD_SERVICE_H_
  
  #include <memory>
  #include <set>
  
  #include "base/callback_forward.h"
  #include "base/macros.h"
  #include "base/memory/shared_memory.h"
  #include "base/memory/singleton.h"
  #include "base/threading/thread_checker.h"
  #include "content/common/content_export.h"
  #include "device/gamepad/gamepad_provider.h"
  
  namespace blink {
  class WebGamepad;
  }
  
  namespace device {
  class GamepadConsumer;
  class GamepadDataFetcher;
  class GamepadProvider;
  }
  
  namespace content {
  
  class GamepadServiceTestConstructor;
  class RenderProcessHost;
  
  // Owns the GamepadProvider (the background polling thread) and keeps track of
  // the number of consumers currently using the data (and pausing the provider
  // when not in use).
  class CONTENT_EXPORT GamepadService
      : public device::GamepadConnectionChangeClient {
   public:
    // Returns the GamepadService singleton.
    static GamepadService* GetInstance();
  
    // Increments the number of users of the provider. The Provider is running
    // when there's > 0 users, and is paused when the count drops to 0.
    // consumer is registered to listen for gamepad connections. If this is the
    // first time it is added to the set of consumers it will be treated
    // specially: it will not be informed about connections before a new user
    // gesture is observed at which point it will be notified for every connected
    // gamepads.
    //
    // Must be called on the I/O thread.
    void ConsumerBecameActive(device::GamepadConsumer* consumer);
  
    // Decrements the number of users of the provider. consumer will not be
    // informed about connections until it's added back via ConsumerBecameActive.
    // Must be matched with a ConsumerBecameActive call.
    //
    // Must be called on the I/O thread.
    void ConsumerBecameInactive(device::GamepadConsumer* consumer);
  
    // Decrements the number of users of the provider and removes consumer from
    // the set of consumers. Should be matched with a a ConsumerBecameActive
    // call.
    //
    // Must be called on the I/O thread.
    void RemoveConsumer(device::GamepadConsumer* consumer);
  
    // Registers the given closure for calling when the user has interacted with
    // the device. This callback will only be issued once. Should only be called
    // while a consumer is active.
    void RegisterForUserGesture(const base::Closure& closure);
  
    // Returns the shared memory handle of the gamepad data duplicated into the
    // given process.
    base::SharedMemoryHandle GetSharedMemoryHandleForProcess(
        base::ProcessHandle handle);
  
    // Stop/join with the background thread in GamepadProvider |provider_|.
    void Terminate();
  
    // Called on IO thread when a gamepad is connected.
    void OnGamepadConnected(int index, const blink::WebGamepad& pad);
  
    // Called on IO thread when a gamepad is disconnected.
    void OnGamepadDisconnected(int index, const blink::WebGamepad& pad);
  
   private:
    friend struct base::DefaultSingletonTraits<GamepadService>;
    friend class GamepadServiceTestConstructor;
    friend class GamepadServiceTest;
  
    GamepadService();
  
    // Constructor for testing. This specifies the data fetcher to use for a
    // provider, bypassing the default platform one.
    GamepadService(
        std::unique_ptr<device::GamepadDataFetcher> fetcher);
  
    virtual ~GamepadService();
  
    static void SetInstance(GamepadService*);
  
    void OnUserGesture();
  
    void OnGamepadConnectionChange(bool connected,
                                   int index,
                                   const blink::WebGamepad& pad) override;
  
    void SetSanitizationEnabled(bool sanitize);
  
    struct ConsumerInfo {
      ConsumerInfo(device::GamepadConsumer* consumer)
          : consumer(consumer), did_observe_user_gesture(false) {}
  
      bool operator<(const ConsumerInfo& other) const {
        return consumer < other.consumer;
      }
  
      device::GamepadConsumer* consumer;
      mutable bool is_active;
      mutable bool did_observe_user_gesture;
    };
  
    std::unique_ptr<device::GamepadProvider> provider_;
  
    base::ThreadChecker thread_checker_;
  
    typedef std::set<ConsumerInfo> ConsumerSet;
    ConsumerSet consumers_;
  
    int num_active_consumers_;
  
    bool gesture_callback_pending_;
  
    DISALLOW_COPY_AND_ASSIGN(GamepadService);
  };
  
  }  // namespace content
  
  #endif  // CONTENT_BROWSER_GAMEPAD_GAMEPAD_SERVICE_H_
  