Sync NaCl MediaStream Video example with ppapi/examples/media_stream_video

native_client_sdk/src/examples/api/media_stream_video/example.js

 // Copyright 2014 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.
 
 var stream;
 
 function success(s) {
   stream = s;
-  common.naclModule.postMessage({track: stream.getVideoTracks()[0]});
+  common.naclModule.postMessage({
+    command: 'init',
+    track: stream.getVideoTracks()[0]
+  });
 }
 
 function failure(e) {
   common.logMessage("Error: " + e);
 }
 
 function moduleDidLoad() {
   navigator.webkitGetUserMedia({'video': true}, success, failure);
 }
+
+function changeFormat(format) {
+  common.naclModule.postMessage({command:'format', format: format});
+}
+
+function changeSize(width, height) {
+  common.naclModule.postMessage({command:'size', width: width, height: height});
+}
+