Make registering custom hooks with schema_generated_bindings.js safer and

chrome/renderer/resources/extensions/page_capture_custom_bindings.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.
 
 // Custom bindings for the pageCapture API.
 
 (function() {
 
 native function GetChromeHidden();
 native function CreateBlob(filePath);
 native function SendResponseAck(requestId);
 
 var chromeHidden = GetChromeHidden();
 
 chromeHidden.registerCustomHook('pageCapture', function(bindingsAPI) {
   var apiFunctions = bindingsAPI.apiFunctions;
 
-  apiFunctions.setCustomCallback(
-      "pageCapture.saveAsMHTML", function(name, request, response) {
+  apiFunctions.setCustomCallback('saveAsMHTML',
+                                 function(name, request, response) {
     var params = chromeHidden.JSON.parse(response);
     var path = params.mhtmlFilePath;
     var size = params.mhtmlFileLength;
 
     if (request.callback)
       request.callback(CreateBlob(path, size));
     request.callback = null;
 
     // Notify the browser. Now that the blob is referenced from JavaScript,
     // the browser can drop its reference to it.
     SendResponseAck(request.id);
   });
 });
 
 })();