Release the camera when WebRTC is not visible in Android

content/browser/renderer_host/media/video_capture_controller.h

Index: content/browser/renderer_host/media/video_capture_controller.h
diff --git a/content/browser/renderer_host/media/video_capture_controller.h b/content/browser/renderer_host/media/video_capture_controller.h
index 2de5ff6bbf795cc898029dfd1afca9108015f281..2cc119d45b4bf5c3c390766898910fc2814e9d20 100644
--- a/content/browser/renderer_host/media/video_capture_controller.h
+++ b/content/browser/renderer_host/media/video_capture_controller.h
@@ -96,8 +96,16 @@ class CONTENT_EXPORT VideoCaptureController {
   int RemoveClient(const VideoCaptureControllerID& id,
                    VideoCaptureControllerEventHandler* event_handler);
 
+  // Pause or resume the video capture for specified client.

[tommi (sloooow) - chröme, 2014/10/01 07:17:03]

Can you document the side effects of this?
(assuming my understanding is correct) If we pause, we don't hold on to the
camera anymore, so resuming might fail and might also take much longer than
pause/play usually does (which I'm guessing is the reason you're calling it
'resume' which I think is good).

[michaelbai, 2014/10/01 22:09:33]

Thanks, I added the side effect in VideoCaptureManager::ResumeCaptureForClient()
because the camera is allocated there.

There is another issue here, if we can't allocate the camera, the error state
will be send out, the video capture can not be resumed automatically any more,
because all information was cleaned up. I were thinking developer could handle
this case by hooking into page visibility API and tried to recreate the video
channel, sounds good?

If we want video capture still resume-able, we need a way to let user know the
camera is occupied by other app so the camera could be released, it seems to me
we don't have that event in JavaScript API ( I assume VIDEO_CAPTURE_STATE_ERROR
is not suitable for this). If we don't notify this to user, there are less
chance camera will be released.

Actually, this issue is not critical, I will explain to you offline.  


On 2014/10/01 07:17:03, tommi wrote:

+  void PauseOrResumeClient(const VideoCaptureControllerID& id,
+                           VideoCaptureControllerEventHandler* event_handler,
+                           bool pause);
+
   int GetClientCount();
 
+  // Return the number of client that isn't paused.
+  int GetActiveClientCount();

[tommi (sloooow) - chröme, 2014/10/01 07:17:03]

const?

[michaelbai, 2014/10/01 22:09:33]

Done.

+
   // API called directly by VideoCaptureManager in case the device is
   // prematurely closed.
   void StopSession(int session_id);