Plumb audio focus support for spitzer clients.

media/blink/webaudiosourceprovider_impl.h

Index: media/blink/webaudiosourceprovider_impl.h
diff --git a/media/blink/webaudiosourceprovider_impl.h b/media/blink/webaudiosourceprovider_impl.h
index afdf1e3ce8dc6364b5c0d3d5b80e45084a1bf2d2..6c54b73768b7dfaf88096c56978548a0ee4075f5 100644
--- a/media/blink/webaudiosourceprovider_impl.h
+++ b/media/blink/webaudiosourceprovider_impl.h
@@ -40,6 +40,8 @@ class MEDIA_BLINK_EXPORT WebAudioSourceProviderImpl
   explicit WebAudioSourceProviderImpl(
       const scoped_refptr<RestartableAudioRendererSink>& sink);
 
+  void enable_audio_focus() { enable_audio_focus_ = true; }
+
   // blink::WebAudioSourceProvider implementation.
   void setClient(blink::WebAudioSourceProviderClient* client) override;
   void provideInput(const blink::WebVector<float*>& audio_data,
@@ -85,6 +87,9 @@ class MEDIA_BLINK_EXPORT WebAudioSourceProviderImpl
   scoped_refptr<RestartableAudioRendererSink> sink_;
   scoped_ptr<AudioBus> bus_wrapper_;
 
+  // If true, Initialize() will set AudioParamaters::FOCUSABLE.
+  bool enable_audio_focus_;
+
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<WebAudioSourceProviderImpl> weak_factory_;