Add support for switching the audio output device for HTMLMediaElements.

media/base/pipeline.cc

Index: media/base/pipeline.cc
diff --git a/media/base/pipeline.cc b/media/base/pipeline.cc
index 4a397049fc0279f9443de4480d02543ce7135cd4..f49e44dd5d4f650f2ed6537879ec30373089ae52 100644
--- a/media/base/pipeline.cc
+++ b/media/base/pipeline.cc
@@ -159,6 +159,23 @@ void Pipeline::SetVolume(float volume) {
   }
 }
 
+void Pipeline::SwitchAudioOutputDevice(
+    const std::string& device_id,
+    const GURL& security_origin,
+    const base::Callback<void(int)>& callback) {
+  DVLOG(1) << __FUNCTION__;
+  base::AutoLock auto_lock(lock_);
+  if (running_) {
+    task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(&Pipeline::AudioOutputDeviceSwitchedTask,
+                   weak_factory_.GetWeakPtr(),
+                   device_id,
+                   security_origin,
+                   callback));
+  }
+}
+
 TimeDelta Pipeline::GetMediaTime() const {
   base::AutoLock auto_lock(lock_);
   return renderer_ ? std::min(renderer_->GetMediaTime(), duration_)
@@ -572,6 +589,19 @@ void Pipeline::VolumeChangedTask(float volume) {
   renderer_->SetVolume(volume);
 }
 
+void Pipeline::AudioOutputDeviceSwitchedTask(
+    const std::string& device_id,
+    const GURL& security_origin,
+    const base::Callback<void(int)>& callback) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  DVLOG(1) << __FUNCTION__ << "(" << device_id << ", "
+           << security_origin << ")";
+
+  // TODO(guidou): Check if there are any values of state_ for which switching

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

Please do this in the current CL, or submit a crbug and note the bug number
here.

+  // audio output device makes no sense.
+  renderer_->SwitchAudioOutputDevice(device_id, security_origin, callback);
+}
+
 void Pipeline::SeekTask(TimeDelta time, const PipelineStatusCB& seek_cb) {
   DCHECK(task_runner_->BelongsToCurrentThread());
   DCHECK(stop_cb_.is_null());