Pass camera facing info to audio client

media/base/video_facing.h

 // Copyright 2017 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.
 
 #ifndef MEDIA_BASE_VIDEO_FACING_H_
 #define MEDIA_BASE_VIDEO_FACING_H_
 
+#if defined(OS_CHROMEOS)
+#include "chromeos/audio/cras_audio_handler.h"

[chfremer1, 2017/01/25 18:13:44]

I am not familiar with the dependency structures around chromeos.
But I am surprised that (according to this CL) chromeos is "lower-level" than
media/base, i.e. it is okay for media/base to depend on chromeos and not the
other way around. Can you confirm that this is really the case?

If chromeos could depend on media/base, we could just place the interface
VideoCaptureObserver in here. This would eliminate the need for the adapter
defined below.

[shenghao, 2017/01/29 10:21:02]

Yes, as you can see in https://cs.chromium.org/chromium/src/media/DEPS //media/
depends on //chromeos/audio (//media/base does not have its own DEPS file).

And even if I push the dependency in //media/ to //media/audio, //chromeos/audio
still can't depend on //media/base due to a cyclic dependency.

+#endif
+
 namespace media {
 
 // Facing mode for video capture.
 enum VideoFacingMode {
   MEDIA_VIDEO_FACING_NONE = 0,
   MEDIA_VIDEO_FACING_USER,
   MEDIA_VIDEO_FACING_ENVIRONMENT,
 
   NUM_MEDIA_VIDEO_FACING_MODE
 };
 
+class VideoCaptureObserver {

[chfremer1, 2017/01/25 18:13:44]

It would be cleaner (and make our life easier in testing) if the thing that
VideoCaptureManager takes a dependency on is a pure interface. If we really need
two versions of this interface (one in chromeos:: and one in media::), then the
adapter functionality currently expressed in this class should be separate from
that, i.e. a class

VideoCaptureObserverAdapter : public media::VideoCaptureObserver {
 public:
   ...
 private:
  chromeos::VideoCaptureObserver* observer_;
}

[shenghao, 2017/01/29 10:21:02]

Done.

+ public:
+#if defined(OS_CHROMEOS)
+  VideoCaptureObserver(chromeos::VideoCaptureObserver* observer);
+#endif
+  VideoCaptureObserver();
+  void OnVideoCaptureStarted(VideoFacingMode facing);
+  void OnVideoCaptureStopped(VideoFacingMode facing);
+
+#if defined(OS_CHROMEOS)
+ private:
+  chromeos::VideoCaptureObserver* const observer_;
+#endif
+};
+
 }  // namespace media
 
 #endif  // MEDIA_BASE_VIDEO_FACING_H_