Add support for switching the audio output device for HTMLMediaElements.

media/base/audio_renderer_mixer.h

Index: media/base/audio_renderer_mixer.h
diff --git a/media/base/audio_renderer_mixer.h b/media/base/audio_renderer_mixer.h
index 35ed484976fdb83ee4975b955c10a5e3a296b131..efb7217d6fa9ad1536de39b313cd1703b35f1a9d 100644
--- a/media/base/audio_renderer_mixer.h
+++ b/media/base/audio_renderer_mixer.h
@@ -6,11 +6,13 @@
 #define MEDIA_BASE_AUDIO_RENDERER_MIXER_H_
 
 #include <map>
+#include <string>
 
 #include "base/synchronization/lock.h"
 #include "base/time/time.h"
 #include "media/base/audio_converter.h"
 #include "media/base/audio_renderer_sink.h"
+#include "url/gurl.h"
 
 namespace media {
 
@@ -39,6 +41,10 @@ class MEDIA_EXPORT AudioRendererMixer
     pause_delay_ = delay;
   }
 
+  void SwitchOutputDevice(const std::string& device_id,
+                          const GURL& security_origin,
+                          const base::Callback<void(int)>& callback);
+
  private:
   // AudioRendererSink::RenderCallback implementation.
   int Render(AudioBus* audio_bus, int audio_delay_milliseconds) override;