Remove unused AudioRendererImpl::ResetDecoder() declaration

This declaration appears to be completely unused.

BUG=482085
R=dalecurtis@chromium.org

Review URL: https://codereview.chromium.org/1107263004

Cr-Commit-Position: refs/heads/master@{#327430}

media/renderers/audio_renderer_impl.h

@@ -173,10 +173,6 @@ class MEDIA_EXPORT AudioRendererImpl
   // completed.
   void DoFlush_Locked();
 
-  // Calls |decoder_|.Reset() and arranges for ResetDecoderDone() to get
-  // called when the reset completes.
-  void ResetDecoder();
-
   // Called when the |decoder_|.Reset() has completed.
   void ResetDecoderDone();