Move hello message from It2MeService to It2MeChannel

Currently, Hangouts sends a hello message to the webapp before establishing a long-lived connection.
After this CL, Hangouts will establish the connection first and then send a hello message.  If the
webapp is not installed, Hangouts will receive a disconnect event on the port.  If the webapp is
installed, Hangouts will receive a hello response with the list of supported features.

Review URL: https://codereview.chromium.org/473073002

Cr-Commit-Position: refs/heads/master@{#290127}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@290127 0039d316-1c4b-4281-b951-d872f2087c98

remoting/webapp/background/it2me_helper_channel.js

@@ -10,13 +10,20 @@
  * assistance).
  *
  * It runs in the background page and contains two chrome.runtime.Port objects,
- * respresenting connections to the webapp and hangout, respectively.
+ * representing connections to the webapp and hangout, respectively.
  *
- * Connection is always initiated from Hangouts.
+ * Connection is always initiated from Hangouts by calling
+ *   var port = chrome.runtime.connect({name:'it2me.helper.hangout'}, extId).
+ *   port.postMessage('hello')
+ * If the webapp is not installed, |port.onDisconnect| will fire.
+ * If the webapp is installed, Hangouts will receive a hello response with the
+ * list of supported features.
  *
  *   Hangout                     It2MeHelperChannel        Chrome Remote Desktop
  *      |-----runtime.connect() ------>|                                |
- *      |------connect message-------->|                                |
+ *      |--------hello message-------->|                                |
+ *      |                              |<-----helloResponse message-----|
+ *      |-------connect message------->|                                |
  *      |                              |-------appLauncher.launch()---->|
  *      |                              |<------runtime.connect()------- |
  *      |                              |<-----sessionStateChanged------ |
@@ -109,10 +116,17 @@ remoting.It2MeHelperChannel =
 
 /** @enum {string} */
 remoting.It2MeHelperChannel.HangoutMessageTypes = {
+  HELLO: 'hello',
+  HELLO_RESPONSE: 'helloResponse',
   CONNECT: 'connect',
   DISCONNECT: 'disconnect'
 };
 
+/** @enum {string} */
+remoting.It2MeHelperChannel.Features = {
+  REMOTE_ASSISTANCE: 'remoteAssistance'
+};
+
 /** @enum {string} */
 remoting.It2MeHelperChannel.WebappMessageTypes = {
   SESSION_STATE_CHANGED: 'sessionStateChanged'
@@ -143,7 +157,14 @@ remoting.It2MeHelperChannel.prototype.onHangoutMessage_ = function(message) {
       case MessageTypes.DISCONNECT:
         this.closeWebapp_(message);
         return true;
+      case MessageTypes.HELLO:
+        this.hangoutPort_.postMessage({
+          method: MessageTypes.HELLO_RESPONSE,
+          supportedFeatures: base.values(remoting.It2MeHelperChannel.Features)
+        });
+        return true;
     }
+    throw new Error('Unknown message method=' + message.method);
   } catch(e) {
     var error = /** @type {Error} */ e;
     console.error(error);

remoting/webapp/background/it2me_service.js

@@ -35,7 +35,6 @@ remoting.It2MeService = function(appLauncher) {
   this.helpee_ = null;
 
   this.onWebappConnectRef_ = this.onWebappConnect_.bind(this);
-  this.onMessageExternalRef_ = this.onMessageExternal_.bind(this);
   this.onConnectExternalRef_ = this.onConnectExternal_.bind(this);
 };
 
@@ -51,52 +50,15 @@ remoting.It2MeService.ConnectionTypes = {
  */
 remoting.It2MeService.prototype.init = function() {
   chrome.runtime.onConnect.addListener(this.onWebappConnectRef_);
-  chrome.runtime.onMessageExternal.addListener(this.onMessageExternalRef_);
   chrome.runtime.onConnectExternal.addListener(this.onConnectExternalRef_);
 };
 
 remoting.It2MeService.prototype.dispose = function() {
   chrome.runtime.onConnect.removeListener(this.onWebappConnectRef_);
-  chrome.runtime.onMessageExternal.removeListener(
-      this.onMessageExternalRef_);
   chrome.runtime.onConnectExternal.removeListener(
       this.onConnectExternalRef_);
 };
 
-/**
- * This function is called when a runtime message is received from an external
- * web page (hangout) or extension.
- *
- * @param {{method:string, data:Object.<string,*>}} message
- * @param {chrome.runtime.MessageSender} sender
- * @param {function(*):void} sendResponse
- * @private
- */
-remoting.It2MeService.prototype.onMessageExternal_ =
-    function(message, sender, sendResponse) {
-  try {
-    var method = message.method;
-    if (method == 'hello') {
-      // The hello message is used by hangouts to detect whether the app is
-      // installed and what features are supported.
-      sendResponse({
-        method: 'helloResponse',
-        supportedFeatures: ['it2me']
-      });
-      return true;
-    }
-    throw new Error('Unknown method: ' + method);
-  } catch (e) {
-    var error = /** @type {Error} */ e;
-    console.error(error);
-    sendResponse({
-      method: message.method + 'Response',
-      error: error.message
-    });
-  }
-  return false;
-};
-
 /**
  * This function is called when Hangouts connects via chrome.runtime.connect.
  * Only web pages that are white-listed in the manifest are allowed to connect.

remoting/webapp/unittests/it2me_helper_channel_unittest.js

@@ -61,6 +61,16 @@ function promiseResolveSynchronous(value) {
   };
 }
 
+test('onHangoutMessage_("hello") should return supportedFeatures', function() {
+  hangoutPort.onMessage.mock$fire(
+      { method: remoting.It2MeHelperChannel.HangoutMessageTypes.HELLO });
+
+  sinon.assert.calledWith(hangoutPort.postMessage, {
+    method: remoting.It2MeHelperChannel.HangoutMessageTypes.HELLO_RESPONSE,
+    supportedFeatures: base.values(remoting.It2MeHelperChannel.Features)
+  });
+});
+
 test('onHangoutMessage_(|connect|) should launch the webapp',
     function() {
   sinon.assert.called(appLauncher.launch);

remoting/webapp/unittests/it2me_service_unittest.js

@@ -129,17 +129,4 @@ test('should reject unknown connection', function() {
   sinon.assert.called(randomPort.disconnect);
 });
 
-test('messageExternal("hello") should return supportedFeatures', function() {
-  var response = null;
-  function callback(msg) {
-    response = msg;
-  }
-
-  it2meService.onMessageExternal_({
-    method: 'hello'
-  }, null, callback);
-
-  QUnit.ok(response.supportedFeatures instanceof Array);
-});
-
 })();