Add a Record button to the web-app if the host supports video recording.

remoting/webapp/js_proto/chrome_proto.js

Index: remoting/webapp/js_proto/chrome_proto.js
diff --git a/remoting/webapp/js_proto/chrome_proto.js b/remoting/webapp/js_proto/chrome_proto.js
index ba9d3bbc7ac5962e8950971f8a5ac11c2b29925c..c7d983fdeffd5aef844f117ddb84c2ad70edfcc0 100644
--- a/remoting/webapp/js_proto/chrome_proto.js
+++ b/remoting/webapp/js_proto/chrome_proto.js
@@ -241,6 +241,20 @@ OnClickData.prototype.checked;
 
 
 /** @type {Object} */
+chrome.fileSystem = {
+  /**
+   * @param {Object.<string>?} options
+   * @param {function(Entry, Array.<FileEntry>):void} callback
+   */
+  chooseEntry: function(options, callback) {},
+  /**
+   * @param {FileEntry} fileEntry
+   * @param {function(string):void} callback
+   */
+  getDisplayPath: function(fileEntry, callback) {}
+};
+
+/** @type {Object} */
 chrome.identity = {
   /**
    * @param {Object.<string>} parameters
@@ -507,4 +521,3 @@ chrome.cast.initialize =
  */
 chrome.cast.requestSession =
     function(successCallback, errorCallback) {};
-