Plugin Power Saver: Mute throttled plugins.

ppapi/shared_impl/ppb_audio_shared.h

Index: ppapi/shared_impl/ppb_audio_shared.h
diff --git a/ppapi/shared_impl/ppb_audio_shared.h b/ppapi/shared_impl/ppb_audio_shared.h
index 31888c882645fded45167c6de33fe941f97506d9..cad9a554d52fd9ddb8b22529b89cb26a52164cb5 100644
--- a/ppapi/shared_impl/ppb_audio_shared.h
+++ b/ppapi/shared_impl/ppb_audio_shared.h
@@ -8,6 +8,7 @@
 #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"
@@ -92,6 +93,13 @@ class PPAPI_SHARED_EXPORT PPB_Audio_Shared
   // 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();
@@ -105,6 +113,10 @@ class PPAPI_SHARED_EXPORT PPB_Audio_Shared
   // 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_;