Replace AudioSilenceDetector with an AudioPowerMonitor.

content/browser/renderer_host/media/audio_renderer_host.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.
 //
 // AudioRendererHost serves audio related requests from AudioRenderer which
 // lives inside the render process and provide access to audio hardware.
 //
 // This class is owned by BrowserRenderProcessHost, and instantiated on UI
 // thread, but all other operations and method calls happen on IO thread, so we
 // need to be extra careful about the lifetime of this object. AudioManager is a
@@ skipping 101 matching lines @@
   void OnCloseStream(int stream_id);
 
   // Set the volume of the audio stream referenced by |stream_id|.
   void OnSetVolume(int stream_id, double volume);
 
   // Complete the process of creating an audio stream. This will set up the
   // shared memory or shared socket in low latency mode and send the
   // NotifyStreamCreated message to the peer.
   void DoCompleteCreation(AudioEntry* entry);
 
-  // Propagate audible signal to MediaObserver.
-  void DoNotifyAudibleState(AudioEntry* entry, bool is_audible);
+  // Propagate measured power level of the audio signal to MediaObserver.
+  void DoNotifyAudioPowerLevel(AudioEntry* entry, float power_in_dbfs);
 
   // Send an error message to the renderer.
   void SendErrorMessage(int stream_id);
 
   // Delete an audio entry, notifying observers first.  This is called by
   // AudioOutputController after it has closed.
   void DeleteEntry(scoped_ptr<AudioEntry> entry);
 
   // Send an error message to the renderer, then close the stream.
   void ReportErrorAndClose(int stream_id);
@@ skipping 11 matching lines @@
 
   // A map of stream IDs to audio sources.
   AudioEntryMap audio_entries_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioRendererHost);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_RENDERER_HOST_H_