Implicit audio output device selection for getUserMedia.

content/browser/renderer_host/media/audio_renderer_host.cc

Index: content/browser/renderer_host/media/audio_renderer_host.cc
diff --git a/content/browser/renderer_host/media/audio_renderer_host.cc b/content/browser/renderer_host/media/audio_renderer_host.cc
index 1e1065aca5e225a3d75ca4f006553ece32771cff..c09dc6ce08b00df873adee71e86cd47da72099c3 100644
--- a/content/browser/renderer_host/media/audio_renderer_host.cc
+++ b/content/browser/renderer_host/media/audio_renderer_host.cc
@@ -36,6 +36,7 @@ class AudioRendererHost::AudioEntry
              int stream_id,
              int render_view_id,
              const media::AudioParameters& params,
+             const std::string& output_device_id,
              const std::string& input_device_id,
              scoped_ptr<base::SharedMemory> shared_memory,
              scoped_ptr<media::AudioOutputController::SyncReader> reader);
@@ -88,6 +89,7 @@ class AudioRendererHost::AudioEntry
 AudioRendererHost::AudioEntry::AudioEntry(
     AudioRendererHost* host, int stream_id, int render_view_id,
     const media::AudioParameters& params,
+    const std::string& output_device_id,
     const std::string& input_device_id,
     scoped_ptr<base::SharedMemory> shared_memory,
     scoped_ptr<media::AudioOutputController::SyncReader> reader)
@@ -95,8 +97,7 @@ AudioRendererHost::AudioEntry::AudioEntry(
       stream_id_(stream_id),
       render_view_id_(render_view_id),
       controller_(media::AudioOutputController::Create(
-          // TODO(tommi): Feed in the proper output device id.
-          host->audio_manager_, this, params, std::string(),
+          host->audio_manager_, this, params, output_device_id,
           input_device_id, reader.get())),
       shared_memory_(shared_memory.Pass()),
       reader_(reader.Pass()) {
@@ -303,10 +304,16 @@ void AudioRendererHost::OnCreateStream(
 
   // When the |input_channels| is valid, clients are trying to create a unified
   // IO stream which opens an input device mapping to the |session_id|.
-  std::string input_device_id;
+  // Initialize the |output_device_id| to an empty string which indicates that
+  // the default device should be used. If a StreamDeviceInfo instance was found
+  // though, then we use the matched output device.
+  std::string input_device_id, output_device_id;
+  const StreamDeviceInfo* info = media_stream_manager_->
+      audio_input_device_manager()->GetOpenedDeviceInfoById(session_id);
+  if (info)
+    output_device_id = info->device.matched_output_device_id;
+
   if (input_channels > 0) {
-    const StreamDeviceInfo* info = media_stream_manager_->
-        audio_input_device_manager()->GetOpenedDeviceInfoById(session_id);
     if (!info) {
       SendErrorMessage(stream_id);
       DLOG(WARNING) << "No permission has been granted to input stream with "
@@ -348,8 +355,8 @@ void AudioRendererHost::OnCreateStream(
     media_observer->OnCreatingAudioStream(render_process_id_, render_view_id);
 
   scoped_ptr<AudioEntry> entry(new AudioEntry(
-      this, stream_id, render_view_id, params, input_device_id,
-      shared_memory.Pass(),
+      this, stream_id, render_view_id, params, output_device_id,
+      input_device_id, shared_memory.Pass(),
       reader.PassAs<media::AudioOutputController::SyncReader>()));
   if (mirroring_manager_) {
     mirroring_manager_->AddDiverter(