Disable Hangouts Remote Desktop Integration until it passes security review

Hangout Remote Desktop integration is no longer targetting M39.
Since it hasn't gone through security review yet, we should disable the
feature until we got a sign off from security.

BUG=414463

Review URL: https://codereview.chromium.org/572083002

Cr-Commit-Position: refs/heads/master@{#294976}

remoting/webapp/background/background.js

@@ -60,15 +60,19 @@ function initializeBackgroundService(appLauncher) {
 }
 
 function main() {
-  /** @type {remoting.AppLauncher} */
-  var appLauncher = new remoting.V1AppLauncher();
   if (base.isAppsV2()) {
     appLauncher = new remoting.V2AppLauncher();
     initializeAppV2(appLauncher);
   }
-  initializeBackgroundService(appLauncher);
 }
 
+remoting.enableHangoutsRemoteAssistance = function() {
+  /** @type {remoting.AppLauncher} */
+  var appLauncher = base.isAppsV2() ? new remoting.V1AppLauncher():
+                                      new remoting.V2AppLauncher();
+  initializeBackgroundService(appLauncher);
+};
+
 window.addEventListener('load', main, false);
 
 }());