[Chromoting] Convert VideoFrameRecorder into a proper protocol extension.

remoting/webapp/crd/js/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
+ * @implements {remoting.ProtocolExtension}
  */
-remoting.VideoFrameRecorder = function(plugin) {
+remoting.VideoFrameRecorder = function() {
+  /** @private {?function(string,string)} */
+  this.sendMessageToHostCallback_ = null;
+
   this.fileWriter_ = null;
   this.isRecording_ = false;
-  this.plugin_ = plugin;
+};
+
+/** @private {string} */
+remoting.VideoFrameRecorder.EXTENSION_TYPE = 'video-recorder';
+
+/** @return {Array<string>} */
+remoting.VideoFrameRecorder.prototype.getExtensionTypes = function() {
+  return [remoting.VideoFrameRecorder.EXTENSION_TYPE];
 };
 
 /**
- * Starts or stops video recording.
+ * @param {function(string,string)} sendMessageToHost Callback to send a message
+ *     to the host.
  */
-remoting.VideoFrameRecorder.prototype.startStopRecording = function() {
-  var data = {};
-  if (this.isRecording_) {
-    this.isRecording_ = false;
-    data = { type: 'stop' }
+remoting.VideoFrameRecorder.prototype.startExtension =
+    function(sendMessageToHost) {
+  this.sendMessageToHostCallback_ = sendMessageToHost;
+};
 
-    chrome.fileSystem.chooseEntry(
-        {type: 'saveFile', suggestedName: 'videoRecording.pb'},
-        this.onFileChosen_.bind(this));
-  } else {
-    this.isRecording_ = true;
-    data = { type: 'start' }
-  }
-  this.plugin_.sendClientMessage('video-recorder', JSON.stringify(data));
+/**
+ * @param {Object} data The data to send.
+ * @private
+ */
+remoting.VideoFrameRecorder.prototype.sendMessageToHost_ = function(data) {
+  this.sendMessageToHostCallback_(remoting.VideoFrameRecorder.EXTENSION_TYPE,
+                                  JSON.stringify(data));
 }
 
 /**
- * Returns true if the session is currently being recorded.
- * @return {boolean}
- */
-remoting.VideoFrameRecorder.prototype.isRecording = function() {
-  return this.isRecording_;
-}
-
-/**
  * Handles 'video-recorder' extension messages and returns true. Returns
  * false for all other message types.
  *
  * @param {string} type Type of extension message.
  * @param {Object} message The parsed extension message data.
  * @return {boolean}
  */
-remoting.VideoFrameRecorder.prototype.handleMessage =
+remoting.VideoFrameRecorder.prototype.onExtensionMessage =
     function(type, message) {
-  if (type != 'video-recorder') {
-    return false;
-  }
+  base.debug.assert(type == remoting.VideoFrameRecorder.EXTENSION_TYPE);
 
   var messageType = base.getStringAttr(message, 'type');
   var messageData = base.getStringAttr(message, 'data');
 
   if (messageType == 'next-frame-reply') {
     if (!this.fileWriter_) {
       console.log("Received frame but have no writer");
       return true;
     }
     if (!messageData) {
@@ skipping 33 matching lines @@
     this.fileWriter_.write(videoPacketBlob);
 
     return true;
   }
 
   console.log("Unrecognized message: " + messageType);
   return true;
 }
 
 /**
+ * Starts or stops video recording.
+ */
+remoting.VideoFrameRecorder.prototype.startStopRecording = function() {
+  var data = {};
+  if (this.isRecording_) {
+    this.isRecording_ = false;
+    data = { type: 'stop' }
+
+    chrome.fileSystem.chooseEntry(
+        {type: 'saveFile', suggestedName: 'videoRecording.pb'},
+        this.onFileChosen_.bind(this));
+  } else {
+    this.isRecording_ = true;
+    data = { type: 'start' }
+  }
+  this.sendMessageToHost_(data);
+}
+
+/**
+ * Returns true if the session is currently being recorded.
+ * @return {boolean}
+ */
+remoting.VideoFrameRecorder.prototype.isRecording = function() {
+  return this.isRecording_;
+}
+
+/**
  * @param {Entry} entry The single file entry if multiple files are not allowed.
  * @param {Array<FileEntry>} fileEntries List of file entries if multiple files
  *     are allowed.
  */
 remoting.VideoFrameRecorder.prototype.onFileChosen_ = function(
     entry, fileEntries) {
   if (!entry) {
     console.log("Cancelled save of video frames.");
   } else {
     chrome.fileSystem.getDisplayPath(entry, function(path) {
@@ skipping 12 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));
+  this.sendMessageToHost_(data);
 }