[GCM] Updating the list of restricted keys for GCM API messages

chrome/renderer/resources/extensions/gcm_custom_bindings.js

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Custom binding for the GCM API.
 
 var binding = require('binding').Binding.create('gcm');
 var forEach = require('utils').forEach;
 
 binding.registerCustomHook(function(bindingsAPI) {
   var apiFunctions = bindingsAPI.apiFunctions;
   var gcm = bindingsAPI.compiledApi;
 
   apiFunctions.setUpdateArgumentsPostValidate(
     'send', function(message, callback) {
       // Validate message.data.
       var payloadSize = 0;
       forEach(message.data, function(property, value) {
         if (property.length == 0)
           throw new Error("One of data keys is empty.");
 
+        var lowerCasedProperty = property.toLowerCase();
         // Issue an error for forbidden prefixes of property names.
-        if (property.indexOf("goog.") == 0 ||
-            property.indexOf("google") == 0) {
+        if (lowerCasedProperty.indexOf("goog.") == 0 ||
+            lowerCasedProperty.indexOf("google") == 0 ||
+            property.indexOf("collapse_key") == 0) {
           throw new Error("Invalid data key: " + property);
         }
 
         payloadSize += property.length + value.length;
       });
 
       if (payloadSize > gcm.MAX_MESSAGE_SIZE)
         throw new Error("Payload exceeded allowed size limit. Payload size is: "
             + payloadSize);
 
       if (payloadSize == 0)
         throw new Error("No data to send.");
 
       return arguments;
     });
 });
 
 exports.binding = binding.generate();