Pass camera facing info to audio client

chromeos/dbus/cras_audio_client.h

Index: chromeos/dbus/cras_audio_client.h
diff --git a/chromeos/dbus/cras_audio_client.h b/chromeos/dbus/cras_audio_client.h
index 54284be264527ddf2c489aff2ccea02a2e2678b2..10f549c6778ce9dd5f9afb3c20583a0cf158ec55 100644
--- a/chromeos/dbus/cras_audio_client.h
+++ b/chromeos/dbus/cras_audio_client.h
@@ -49,6 +49,8 @@ class CHROMEOS_EXPORT CrasAudioClient : public DBusClient {
     virtual ~Observer();
   };
 
+  enum VideoFacingMode { NONE = 0, USER, ENVIRONMENT };

[jennyz, 2017/01/18 00:01:37]

First: CrasAudioClient is a thin wrap for cras dbus API logic. It is not
appropriate to add other device logic here. A better place will be
CrasAudioHandler. 

Second: VideoFacingMode is better to be defined in the camera related class
instead of audio related class. '

Third: What is USER and ENVIRONMENT facing mode really mean?

[shenghao, 2017/01/18 10:41:12]

Moved to CrasAudioHandler
We already have a shared VideoFacingMode defined in //media/base. But since it
can't be included here, I am defining a new one, and I imagine that this
VideoFacingMode will only be used within CrasAudioHandler, so it seems more
natural to define it here. If you think there are other appropriate video
related classes in //chromeos world, please suggest.
Added comments. The naming is consistent with the enum in //media/base and in
Webkit.

+
   ~CrasAudioClient() override;
 
   // Adds and removes the observer.
@@ -57,6 +59,8 @@ class CHROMEOS_EXPORT CrasAudioClient : public DBusClient {
   // Returns true if this object has the given observer.
   virtual bool HasObserver(const Observer* observer) const = 0;
 
+  virtual void OnVideoCaptureStarted(VideoFacingMode facing) {}

[jennyz, 2017/01/18 00:01:37]

Move this to CrasAudioHandler.

[shenghao, 2017/01/18 10:41:12]

Done.

+
   // GetVolumeStateCallback is used for GetVolumeState method. It receives
   // 2 arguments, |volume_state| which containing both input and  output volume
   // state data, and |success| which indicates whether or not the request