Add support for switching the audio output device for HTMLMediaElements.

media/base/audio_renderer_mixer.cc

 // 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.
 
 #include "media/base/audio_renderer_mixer.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/logging.h"
 
@@ skipping 53 matching lines @@
     if (it->Equals(error_cb)) {
       error_callbacks_.erase(it);
       return;
     }
   }
 
   // An error callback should always exist when called.
   NOTREACHED();
 }
 
+void AudioRendererMixer::SwitchOutputDevice(
+    const std::string& device_id,
+    const GURL& security_origin,
+    const base::Callback<void(int)>& callback) {
+  DVLOG(1) << __FUNCTION__ << "(" << device_id << ", "
+           << security_origin << ")";
+  base::AutoLock auto_lock(lock_);
+  audio_sink_->SwitchOutputDevice(device_id, security_origin, callback);
+}
+
+
 int AudioRendererMixer::Render(AudioBus* audio_bus,
                                int audio_delay_milliseconds) {
   base::AutoLock auto_lock(lock_);
 
   // If there are no mixer inputs and we haven't seen one for a while, pause the
   // sink to avoid wasting resources when media elements are present but remain
   // in the pause state.
   const base::TimeTicks now = base::TimeTicks::Now();
   if (!audio_converter_.empty()) {
     last_play_time_ = now;
   } else if (now - last_play_time_ >= pause_delay_ && playing_) {
     audio_sink_->Pause();
     playing_ = false;
   }
 
   audio_converter_.ConvertWithDelay(
       base::TimeDelta::FromMilliseconds(audio_delay_milliseconds), audio_bus);
   return audio_bus->frames();
 }
 
 void AudioRendererMixer::OnRenderError() {
   // Call each mixer input and signal an error.
   base::AutoLock auto_lock(lock_);
   for (const auto& cb : error_callbacks_)
     cb.Run();
 }
 
 }  // namespace media