Plugin Power Saver: Mute throttled plugins.

ppapi/shared_impl/ppb_audio_shared.h

 // 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 PPAPI_SHARED_IMPL_PPB_AUDIO_SHARED_H_
 #define PPAPI_SHARED_IMPL_PPB_AUDIO_SHARED_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/shared_memory.h"
 #include "base/sync_socket.h"
+#include "base/synchronization/lock.h"
 #include "base/threading/simple_thread.h"
 #include "media/base/audio_bus.h"
 #include "ppapi/c/ppb_audio.h"
 #include "ppapi/c/ppb_audio_config.h"
 #include "ppapi/shared_impl/resource.h"
 #include "ppapi/thunk/ppb_audio_api.h"
 
 struct PP_ThreadFunctions;
 
 namespace ppapi {
@@ skipping 64 matching lines @@
 
   // Configures this class to run in a NaCl plugin.
   // If called, SetThreadFunctions() must be called before calling
   // SetStartPlaybackState() on any instance of this class.
   static void SetNaClMode();
 
   // NaCl has a special API for IRT code to create threads that can call back
   // into user code.
   static void SetThreadFunctions(const struct PP_ThreadFunctions* functions);
 
+ protected:
+  // Configures if we zero out the audio buffers after each audio callback.
+  // This is a stopgap to mute individual plugins that in power saver mode.
+  void SetMutedForPowerSaver(bool muted_for_power_saver);
+
+  bool IsMutedForPowerSaver();
+
  private:
   // Starts execution of the audio thread.
   void StartThread();
 
   // Stop execution of the audio thread.
   void StopThread();
 
   // DelegateSimpleThread::Delegate implementation. Run on the audio thread.
   virtual void Run();
 
   // True if playing the stream.
   bool playing_;
 
+  // True if we mute the stream while continuing to play it (for power saver).
+  volatile bool muted_for_power_saver_;

[piman, 2015/01/28 21:58:50]

Why volatile?

+  base::Lock mute_lock_;
+
   // Socket used to notify us when audio is ready to accept new samples. This
   // pointer is created in StreamCreated().
   scoped_ptr<base::CancelableSyncSocket> socket_;
 
   // Sample buffer in shared memory. This pointer is created in
   // StreamCreated(). The memory is only mapped when the audio thread is
   // created.
   scoped_ptr<base::SharedMemory> shared_memory_;
 
   // The size of the sample buffer in bytes.
@@ skipping 24 matching lines @@
 
   // Buffer index used to coordinate with the browser side audio receiver.
   uint32_t buffer_index_;
 
   DISALLOW_COPY_AND_ASSIGN(PPB_Audio_Shared);
 };
 
 }  // namespace ppapi
 
 #endif  // PPAPI_SHARED_IMPL_PPB_AUDIO_SHARED_H_