Translate: cleanup on how to pass api key to the script

chrome/browser/resources/translate.js

 // Copyright (c) 2012 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.
 
 // This code is used in conjunction with the Google Translate Element script.
 // It is executed in an isolated world of a page to translate it from one
 // language to another.
 // It should be included in the page before the Translate Element script.
 
 var cr = {};
 
-cr.googleTranslate = (function(key) {
+/**
+ * An object to provide functions to interact with the Translate library.
+ * @type {object}
+ */
+cr.googleTranslate = (function() {
   /**
    * The Translate Element library's instance.
    * @type {object}
    */
   var lib;
 
   /**
    * A flag representing if the Translate Element library is initialized.
    * @type {boolean}
    */
@@ skipping 229 matching lines @@
     },
 
     /**
      * Entry point called by the Translate Element once it has been injected in
      * the page.
      */
     onTranslateElementLoad: function() {
       loadedTime = performance.now();
       try {
         lib = google.translate.TranslateService({
-          'key': key,
+          // translateApiKey is predefined by translate_script.cc.
+          'key': translateApiKey,
           'useSecureConnection': true
         });
+        delete translateApiKey;

[Evan Stade, 2013/08/12 15:24:46]

what is this supposed to do?

[Takashi Toyoshima, 2013/08/13 01:18:37]

"var translateApiKey = '...';\r\n" is injected before the script by the C++
code.
I want to remove the reference of the string once it is used.
This is not needed actually, but just in case so that there is less chance for
attackers to access the key.

       } catch (err) {
         error = true;
+        delete translateApiKey;
         return;
       }
       // The TranslateService is not available immediately as it needs to start
       // Flash.  Let's wait until it is ready.
       checkLibReady();
     }
   };
-})/* Calling code '(|key|);' will be appended by TranslateHelper in C++ here. */
+})();