Implement externally_connectable! Web pages can now communicate directly with

chrome/renderer/resources/extensions/miscellaneous_bindings.js

Index: chrome/renderer/resources/extensions/miscellaneous_bindings.js
diff --git a/chrome/renderer/resources/extensions/miscellaneous_bindings.js b/chrome/renderer/resources/extensions/miscellaneous_bindings.js
index 6b57e1cd4c7dddef62fe9463ed022f7a2d5d6d72..cf11a6f9c7e8e707d435790798c73aa84ee78415 100644
--- a/chrome/renderer/resources/extensions/miscellaneous_bindings.js
+++ b/chrome/renderer/resources/extensions/miscellaneous_bindings.js
@@ -196,7 +196,9 @@
     // the right event.
     var isExternal = sourceExtensionId != extensionId;
 
-    var sender = {id: sourceExtensionId};
+    var sender = {};
+    if (sourceExtensionId != '')
+      sender.id = sourceExtensionId;
     if (sourceUrl)
       sender.url = sourceUrl;
     if (sourceTab)