Audio related IPC messages and handlers from browser to renderer

media/audio/audio_output.h

Index: media/audio/audio_output.h
diff --git a/media/audio/audio_output.h b/media/audio/audio_output.h
index 12ef3d9907590dc5716c9472f2ecd35ecbc34102..8f95a70ad113d722e9357c10292120fd30ea5c89 100644
--- a/media/audio/audio_output.h
+++ b/media/audio/audio_output.h
@@ -41,6 +41,12 @@
 // a given AudioOutputStream might or might not talk directly to hardware.
 class AudioOutputStream {
  public:
+  enum State {
+    STATE_STARTED = 0,  // The output stream is started.
+    STATE_PAUSED,       // The output stream is paused.
+    STATE_ERROR,        // The output stream is in error state.
+  };
+
   // Audio sources must implement AudioSourceCallback. This interface will be
   // called in a random thread which very likely is a high priority thread. Do
   // not rely on using this thread TLS or make calls that alter the thread