Add support for switching the audio output device for HTMLMediaElements.

media/audio/null_audio_sink.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/audio/null_audio_sink.h"
 
 #include "base/bind.h"
 #include "base/single_thread_task_runner.h"
 #include "media/audio/fake_audio_worker.h"
 #include "media/base/audio_hash.h"
@@ skipping 52 matching lines @@
 
   fake_worker_->Stop();
   playing_ = false;
 }
 
 bool NullAudioSink::SetVolume(double volume) {
   // Audio is always muted.
   return volume == 0.0;
 }
 
+void NullAudioSink::SwitchOutputDevice(
+    const std::string &device_id,
+    const GURL& security_origin,
+    const base::Callback<void(int)>& callback) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+}

[miu, 2015/06/03 21:01:01]

ditto: Run callback.  Maybe the NullAudioSink should just "fake out" a success
code here?

+
+
 void NullAudioSink::CallRender() {
   DCHECK(task_runner_->BelongsToCurrentThread());
 
   int frames_received = callback_->Render(audio_bus_.get(), 0);
   if (!audio_hash_ || frames_received <= 0)
     return;
 
   audio_hash_->Update(audio_bus_.get(), frames_received);
 }
 
 void NullAudioSink::StartAudioHashForTesting() {
   DCHECK(!initialized_);
   audio_hash_.reset(new AudioHash());
 }
 
 std::string NullAudioSink::GetAudioHashForTesting() {
   return audio_hash_ ? audio_hash_->ToString() : std::string();
 }
 
 }  // namespace media