Hack to restrict runtime API to dev channel rather than experimental.

chrome/renderer/resources/extensions/runtime_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 runtime API.
 
 var extensionNatives = requireNative('extension');
 var GetExtensionViews = extensionNatives.GetExtensionViews;
 var chromeHidden = requireNative('chrome_hidden').GetChromeHidden();
 var sendRequest = require('sendRequest').sendRequest;
 
-chromeHidden.registerCustomHook('experimental.runtime', function(bindingsAPI) {
+chromeHidden.registerCustomHook('runtime', function(bindingsAPI) {
   var apiFunctions = bindingsAPI.apiFunctions;
 
   apiFunctions.setCustomCallback('getBackgroundPage',
                                  function(name, request, response) {
     if (request.callback) {
       var bg = GetExtensionViews(-1, 'BACKGROUND')[0] || null;
       request.callback(bg);
     }
     request.callback = null;
   });
 });