[Chromoting] Convert VideoFrameRecorder into a proper protocol extension.

remoting/webapp/crd/js/video_frame_recorder.js

Index: remoting/webapp/crd/js/video_frame_recorder.js
diff --git a/remoting/webapp/crd/js/video_frame_recorder.js b/remoting/webapp/crd/js/video_frame_recorder.js
index a5bceb91029c4f8e365325ab4768a1e2df60de4e..e73c832e26e967776cdf1709d1c665f9878b234f 100644
--- a/remoting/webapp/crd/js/video_frame_recorder.js
+++ b/remoting/webapp/crd/js/video_frame_recorder.js
@@ -14,39 +14,40 @@ 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' }
-
-    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));
-}
+remoting.VideoFrameRecorder.prototype.startExtension =
+    function(sendMessageToHost) {
+  this.sendMessageToHostCallback_ = sendMessageToHost;
+};
 
 /**
- * Returns true if the session is currently being recorded.
- * @return {boolean}
+ * @param {Object} data The data to send.
+ * @private
  */
-remoting.VideoFrameRecorder.prototype.isRecording = function() {
-  return this.isRecording_;
+remoting.VideoFrameRecorder.prototype.sendMessageToHost_ = function(data) {
+  this.sendMessageToHostCallback_(remoting.VideoFrameRecorder.EXTENSION_TYPE,
+                                  JSON.stringify(data));
 }
 
 /**
@@ -57,11 +58,9 @@ remoting.VideoFrameRecorder.prototype.isRecording = function() {
  * @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');
@@ -115,6 +114,33 @@ remoting.VideoFrameRecorder.prototype.handleMessage =
 }
 
 /**
+ * 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.
@@ -147,5 +173,5 @@ remoting.VideoFrameRecorder.prototype.onWriteComplete_ = function(e) {
 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);
 }