Add GamepadService, owns 1 gamepad bg thread

content/browser/gamepad/gamepad_provider.h

 // Copyright (c) 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.
 
 #ifndef CONTENT_BROWSER_GAMEPAD_PROVIDER_H_
 #define CONTENT_BROWSER_GAMEPAD_PROVIDER_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop_proxy.h"
 #include "base/shared_memory.h"
+#include "base/synchronization/lock.h"
 #include "base/system_monitor/system_monitor.h"
 #include "base/task.h"
 #include "content/browser/gamepad/data_fetcher.h"
 #include "content/common/content_export.h"
 #include "content/common/gamepad_hardware_buffer.h"
 
 namespace base {
 class Thread;
 }
 
 struct GamepadMsg_Updated_Params;
 
 namespace content {
 
 class CONTENT_EXPORT GamepadProvider :
     public base::RefCountedThreadSafe<GamepadProvider>,
     public base::SystemMonitor::DevicesChangedObserver {
  public:
   explicit GamepadProvider(GamepadDataFetcher* fetcher);
 
-  // Starts or Stops the provider. Called from creator_loop_.
-  void Start();
-  void Stop();
   base::SharedMemoryHandle GetRendererSharedMemoryHandle(
       base::ProcessHandle renderer_process);
 
+  // Pause and resume the background polling thread. Can be called from any
+  // thread.
+  void Pause();
+  void Resume();
+
  private:
   friend class base::RefCountedThreadSafe<GamepadProvider>;
 
   virtual ~GamepadProvider();
 
   // Method for starting the polling, runs on polling_thread_.
   void DoInitializePollingThread();
 
   // Method for polling a GamepadDataFetcher. Runs on the polling_thread_.
   void DoPoll();
   void ScheduleDoPoll();
 
   virtual void OnDevicesChanged() OVERRIDE;
 
   GamepadHardwareBuffer* SharedMemoryAsHardwareBuffer();
 
   enum { kDesiredSamplingIntervalMs = 16 };
 
+  // Keeps track of when the background thread is paused. Access to is_paused_
+  // must be guarded by is_paused_lock_.
+  base::Lock is_paused_lock_;
+  bool is_paused_;
+
+  // Updated based on notification from SystemMonitor when the system devices
+  // have been updated, and this notification is passed on to the data fetcher
+  // to enable it to avoid redundant (and possibly expensive) is-connected
+  // tests. Access to devices_changed_ must be guarded by
+  // devices_changed_lock_.
+  base::Lock devices_changed_lock_;
+  bool devices_changed_;
+
   // The Message Loop on which this object was created.
   // Typically the I/O loop, but may be something else during testing.
-  scoped_refptr<base::MessageLoopProxy> creator_loop_;
   scoped_ptr<GamepadDataFetcher> provided_fetcher_;
 
   // When polling_thread_ is running, members below are only to be used
   // from that thread.
   scoped_ptr<GamepadDataFetcher> data_fetcher_;
   base::SharedMemory gamepad_shared_memory_;
-  bool devices_changed_;
 
   // Polling is done on this background thread.
   scoped_ptr<base::Thread> polling_thread_;
 
   static GamepadProvider* instance_;
   base::WeakPtrFactory<GamepadProvider> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(GamepadProvider);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_GAMEPAD_PROVIDER_H_