Interfaceify ClientPlugin in preparation for mocking it.

remoting/webapp/video_frame_recorder.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.
 
 /**
  * @fileoverview
  * Class implement the video frame recorder extension client.
  */
 
 'use strict';
 
 /** @suppress {duplicate} */
 var remoting = remoting || {};
 
 /**
  * @constructor
- * @param {remoting.ClientPlugin} plugin
+ * @param {remoting.ClientPluginInterface} plugin
  */
 remoting.VideoFrameRecorder = function(plugin) {
   this.fileWriter_ = null;
   this.isRecording_ = false;
   this.plugin_ = plugin;
 };
 
 /**
  * Starts or stops video recording.
  */
@@ skipping 115 matching lines @@
 remoting.VideoFrameRecorder.prototype.onWriteComplete_ = function(e) {
   console.log("Video frame write complete");
   this.fetchNextFrame_();
 }
 
 remoting.VideoFrameRecorder.prototype.fetchNextFrame_ = function() {
   console.log("Request next video frame");
   var data = { type: 'next-frame' }
   this.plugin_.sendClientMessage('video-recorder', JSON.stringify(data));
 }