Remove GetVolume from media::AudioRendererSink.

content/renderer/media/audio_device.cc

Index: content/renderer/media/audio_device.cc
diff --git a/content/renderer/media/audio_device.cc b/content/renderer/media/audio_device.cc
index 7365bde690a88376c2280e7091f93f0a9684790a..f02e33f7ae0c81fe608583a7e0e31600e0c92fb0 100644
--- a/content/renderer/media/audio_device.cc
+++ b/content/renderer/media/audio_device.cc
@@ -41,7 +41,6 @@ class AudioDevice::AudioThreadCallback
 AudioDevice::AudioDevice()
     : ScopedLoopObserver(ChildProcess::current()->io_message_loop()),
       callback_(NULL),
-      volume_(1.0),
       stream_id_(0),
       play_on_start_(true),
       is_started_(false) {
@@ -103,16 +102,9 @@ bool AudioDevice::SetVolume(double volume) {
     return false;
   }
 
-  volume_ = volume;
-
   return true;
 }
 
-void AudioDevice::GetVolume(double* volume) {
-  // Return a locally cached version of the current scaling factor.
-  *volume = volume_;
-}
-
 void AudioDevice::CreateStreamOnIOThread(const media::AudioParameters& params) {
   DCHECK(message_loop()->BelongsToCurrentThread());
   // Make sure we don't create the stream more than once.