Reland: Add Stop() to AudioDecoder. (https://codereview.chromium.org/126793002/)

media/filters/audio_renderer_impl.h

Index: media/filters/audio_renderer_impl.h
diff --git a/media/filters/audio_renderer_impl.h b/media/filters/audio_renderer_impl.h
index 851e52b81551f43eb7b7e0e020d6bb85e2c9922f..67f21bd2be95c904483b1a0ea213220d11910a0b 100644
--- a/media/filters/audio_renderer_impl.h
+++ b/media/filters/audio_renderer_impl.h
@@ -97,6 +97,7 @@ class MEDIA_EXPORT AudioRendererImpl
   // TODO(acolwell): Add a state machine graph.
   enum State {
     kUninitialized,
+    kInitializing,
     kPaused,
     kFlushing,
     kPrerolling,
@@ -215,6 +216,9 @@ class MEDIA_EXPORT AudioRendererImpl
   // Callback provided to Flush().
   base::Closure flush_cb_;
 
+  // Callback provided to Stop().
+  base::Closure stop_cb_;
+
   // Callback provided to Preroll().
   PipelineStatusCB preroll_cb_;