CastExtensionHandler for Chromoting Webapp

remoting/webapp/client_plugin.js

Index: remoting/webapp/client_plugin.js
diff --git a/remoting/webapp/client_plugin.js b/remoting/webapp/client_plugin.js
index 7b854a20698c7c7f01b840dfca33f21375e990fb..23896e0b8a5676e4186abde33f16a0589616959b 100644
--- a/remoting/webapp/client_plugin.js
+++ b/remoting/webapp/client_plugin.js
@@ -64,6 +64,9 @@ remoting.ClientPlugin = function(plugin, onExtensionMessage) {
    */
   this.updateMouseCursorImage = function(url, hotspotX, hotspotY) {};
 
+  /** @param {string} data Remote cast extension message. */
+  this.onCastExtensionHandler = function(data) {};
+
   /** @type {remoting.MediaSourceRenderer} */
   this.mediaSourceRenderer_ = null;
 
@@ -221,6 +224,13 @@ remoting.ClientPlugin.prototype.handleMessageMethod_ = function(message) {
       // Let the host know that we can use the video framerecording extension.
       this.capabilities_.push(
           remoting.ClientSession.Capability.VIDEO_RECORDER);
+
+      // Let the host know that we can support casting of the screen.
+      // TODO(aiguha): Add this capability based on a gyp/command-line flag,
+      // rather than by default.
+      this.capabilities_.push(
+          remoting.ClientSession.Capability.CAST);
+
     } else if (this.pluginApiVersion_ >= 6) {
       this.pluginApiFeatures_ = ['highQualityScaling', 'injectKeyEvent'];
     } else {
@@ -315,6 +325,9 @@ remoting.ClientPlugin.prototype.handleMessageMethod_ = function(message) {
       case 'test-echo-reply':
         console.log('Got echo reply: ' + extMsgData);
         break;
+      case 'cast_message':
+        this.onCastExtensionHandler(extMsgData);
+        break;
       default:
         if (!this.onExtensionMessage_(extMsgType, extMsgData)) {
           console.log('Unexpected message received: ' +