Add a new audio extension event OnLevelChanged.

extensions/browser/api/audio/audio_service_chromeos.cc

Index: extensions/browser/api/audio/audio_service_chromeos.cc
diff --git a/extensions/browser/api/audio/audio_service_chromeos.cc b/extensions/browser/api/audio/audio_service_chromeos.cc
index 8005ac69f22175600364894e4e8c047976ce9e33..58b1ff9c35f44c16163c6f26484d7b094e3d1466 100644
--- a/extensions/browser/api/audio/audio_service_chromeos.cc
+++ b/extensions/browser/api/audio/audio_service_chromeos.cc
@@ -17,6 +17,7 @@ namespace extensions {
 
 using core_api::audio::OutputDeviceInfo;
 using core_api::audio::InputDeviceInfo;
+using core_api::audio::AudioDeviceInfo;
 
 class AudioServiceImpl : public AudioService,
                          public chromeos::CrasAudioHandler::AudioObserver {
@@ -35,10 +36,11 @@ class AudioServiceImpl : public AudioService,
                            bool muted,
                            int volume,
                            int gain) override;
+  void StartGetDeviceInfo(const GetDeviceInfoCallback& callback) override;
 
  protected:
   // chromeos::CrasAudioHandler::AudioObserver overrides.
-  void OnOutputVolumeChanged() override;
+  void OnOutputNodeVolumeChanged(uint64 id, double volume) override;
   void OnInputGainChanged() override;
   void OnOutputMuteChanged() override;
   void OnInputMuteChanged() override;
@@ -170,6 +172,45 @@ bool AudioServiceImpl::SetDeviceProperties(const std::string& device_id,
   return false;
 }
 
+void AudioServiceImpl::StartGetDeviceInfo(
+    const GetDeviceInfoCallback& callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  DCHECK(cras_audio_handler_);
+  DCHECK(!callback.is_null());
+
+  if (callback.is_null())
+    return;
+
+  DevicesInfo devices_info;
+  if (!cras_audio_handler_) {
+    callback.Run(devices_info, false);
+    return;
+  }
+
+  chromeos::AudioDeviceList devices;
+  cras_audio_handler_->GetAudioDevices(&devices);
+  for (size_t i = 0; i < devices.size(); ++i) {
+    linked_ptr<AudioDeviceInfo> info(new AudioDeviceInfo());
+    info->id = base::Uint64ToString(devices[i].id);
+    info->display_name = devices[i].display_name;
+    info->device_name = devices[i].device_name;
+    info->is_input = devices[i].is_input;
+    info->is_active = devices[i].active;
+    info->volume_gain =
+        devices[i].is_input
+            ? cras_audio_handler_->GetInputGainPercentForDevice(devices[i].id)
+            : cras_audio_handler_->GetOutputVolumePercentForDevice(
+                  devices[i].id);
+    info->is_muted =
+        devices[i].is_input
+            ? cras_audio_handler_->IsInputMutedForDevice(devices[i].id)
+            : cras_audio_handler_->IsOutputMutedForDevice(devices[i].id);
+    devices_info.push_back(info);
+  }
+
+  callback.Run(devices_info, true);
+}
+
 bool AudioServiceImpl::FindDevice(uint64 id, chromeos::AudioDevice* device) {
   chromeos::AudioDeviceList devices;
   cras_audio_handler_->GetAudioDevices(&devices);
@@ -191,7 +232,13 @@ uint64 AudioServiceImpl::GetIdFromStr(const std::string& id_str) {
     return device_id;
 }
 
-void AudioServiceImpl::OnOutputVolumeChanged() {
+void AudioServiceImpl::OnOutputNodeVolumeChanged(uint64 id, double volume) {
+  FOR_EACH_OBSERVER(
+      AudioService::Observer, observer_list_,
+      OnOutputNodeVolumeChanged(base::Uint64ToString(id), volume));
+
+  // Notify DeviceChanged event for backward compatibility.
+  // TODO(jennyz): remove this code when the old version of hotrod retires.
   NotifyDeviceChanged();
 }