Add support for switching the audio output device for HTMLMediaElements.

media/base/audio_renderer_mixer.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_BASE_AUDIO_RENDERER_MIXER_H_
 #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 {
 
 // Mixes a set of AudioConverter::InputCallbacks into a single output stream
 // which is funneled into a single shared AudioRendererSink; saving a bundle
 // on renderer side resources.
 class MEDIA_EXPORT AudioRendererMixer
     : NON_EXPORTED_BASE(public AudioRendererSink::RenderCallback) {
  public:
   AudioRendererMixer(const AudioParameters& input_params,
                      const AudioParameters& output_params,
                      const scoped_refptr<AudioRendererSink>& sink);
   ~AudioRendererMixer() override;
 
   // Add or remove a mixer input from mixing; called by AudioRendererMixerInput.
   void AddMixerInput(AudioConverter::InputCallback* input);
   void RemoveMixerInput(AudioConverter::InputCallback* input);
 
   // Since errors may occur even when no inputs are playing, an error callback
   // must be registered separately from adding a mixer input.  The same callback
   // must be given to both the functions.
   void AddErrorCallback(const base::Closure& error_cb);
   void RemoveErrorCallback(const base::Closure& error_cb);
 
   void set_pause_delay_for_testing(base::TimeDelta delay) {
     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;
   void OnRenderError() override;
 
   // Output sink for this mixer.
   scoped_refptr<AudioRendererSink> audio_sink_;
 
   // ---------------[ All variables below protected by |lock_| ]---------------
   base::Lock lock_;
@@ skipping 10 matching lines @@
   base::TimeDelta pause_delay_;
   base::TimeTicks last_play_time_;
   bool playing_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioRendererMixer);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_AUDIO_RENDERER_MIXER_H_