Support for multiple VideoCall.Listeners for a VideoCall.

The current code assumes that only a single instance of VideoCall will be
provided to the default system InCall UI.  Ideally multiple
InCallService implementations should be able to use the VideoCall APIs.
Note: it only really makes sense for a single InCallService to get/set
the video surfaces.

- Fixed bug in ParcelableCall which would cause a new instance of
VideoCallImpl to be created every time a call is updated from Telecom.
Added a flag to ParcelableCall to indicate whether the parcel includes a
change to the video provider information, which is used when unparceling
to determine whether to set/create the video call impl.
- Renamed "setVideoCallback" to "addVideocallback".
- Modified Connection.VideoProvider code to keep a list of Video callbacks
and fire off all of them when Video Provider changes occur.

Bug: 20092420
Change-Id: Ic16b6afe1b7532cc64d006c133adbae57946d97d

telecomm/java/android/telecom/VideoCallImpl.java

@@ -166,7 +166,7 @@ public class VideoCallImpl extends VideoCall {
         mVideoProvider.asBinder().linkToDeath(mDeathRecipient, 0);
 
         mBinder = new VideoCallListenerBinder();
-        mVideoProvider.setVideoCallback(mBinder);
+        mVideoProvider.addVideoCallback(mBinder);
     }
 
     /** {@inheritDoc} */
@@ -174,6 +174,15 @@ public class VideoCallImpl extends VideoCall {
         mVideoCallListener = videoCallListener;
     }
 
+    /** {@inheritDoc} */
+    public void removeVideoCallListener() {
+        mVideoCallListener = null;
+        try {
+            mVideoProvider.removeVideoCallback(mBinder);
+        } catch (RemoteException e) {
+        }
+    }
+
     /** {@inheritDoc} */
     public void setCamera(String cameraId) {
         try {