getUserMeida: report device starting states

media/capture/video/android/java/src/org/chromium/media/VideoCaptureCamera.java

Index: media/capture/video/android/java/src/org/chromium/media/VideoCaptureCamera.java
diff --git a/media/capture/video/android/java/src/org/chromium/media/VideoCaptureCamera.java b/media/capture/video/android/java/src/org/chromium/media/VideoCaptureCamera.java
index 929f041150de28ccec086a696f2bc2f219dc9537..fc11b007b9a9a4ca792c47092aed7f10e1d99167 100644
--- a/media/capture/video/android/java/src/org/chromium/media/VideoCaptureCamera.java
+++ b/media/capture/video/android/java/src/org/chromium/media/VideoCaptureCamera.java
@@ -398,6 +398,7 @@ public class VideoCaptureCamera
         mPreviewBufferLock.lock();
         try {
             if (mIsRunning) {
+                nativeOnStarted(mNativeVideoCaptureDeviceAndroid);

[chfremer, 2017/02/16 01:00:50]

Without having tried to read and understand all of this class ...

does this code path mean that is is legal to call startCapture() when 
the device is already started? And if that happens, we are sending out 
another STARTED event to all clients?

If that is the case, the contract would have to state that STARTED 
events may arrive at the clients any number of times while the device 
is running (which would be pretty confusing).

[braveyao, 2017/02/17 20:37:21]

Done.

Anyway, if there are multiple OnStarted events from the same device, but still
only one will be forwarded to VideoCaptureImpl.

                 return true;
             }
             mIsRunning = true;
@@ -411,6 +412,7 @@ public class VideoCaptureCamera
             Log.e(TAG, "startCapture: Camera.startPreview: " + ex);
             return false;
         }
+        nativeOnStarted(mNativeVideoCaptureDeviceAndroid);

[chfremer, 2017/02/16 01:00:50]

It seems that here we invoke OnStarted() after mIsRunning has been set to true
and after mCamera.startPreview() has been called. Can it happen that a frame
from the camera arrives and is sent before this invocation of OnStarted()? If
not, why?

[braveyao, 2017/02/17 20:37:21]

Done.

         return true;
     }