Implement chrome.extension.connectExternal and fix various API inconsistencies.

chrome/renderer/resources/event_bindings.js

Index: chrome/renderer/resources/event_bindings.js
diff --git a/chrome/renderer/resources/event_bindings.js b/chrome/renderer/resources/event_bindings.js
index 3def161f7d300c292ca337e6668f69e76a838ff2..dc69268c34d387d41cb98077eaaa8911d8771bbd 100644
--- a/chrome/renderer/resources/event_bindings.js
+++ b/chrome/renderer/resources/event_bindings.js
@@ -2,11 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// -----------------------------------------------------------------------------
-// NOTE: If you change this file you need to touch renderer_resources.grd to
-// have your change take effect.
-// -----------------------------------------------------------------------------
-
 var chrome = chrome || {};
 (function () {
   native function GetChromeHidden();
@@ -105,6 +100,11 @@ var chrome = chrome || {};
     return this.findListeners_(cb) > -1;
   };
 
+  // Test if any callbacks are registered for this event.
+  chrome.Event.prototype.hasListeners = function(cb) {
+    return this.listeners_.length > 0;
+  };
+
   // Returns the index of the given callback if registered, or -1 if not
   // found.
   chrome.Event.prototype.findListener_ = function(cb) {