Begin to enable extension APIs in Extension Service Worker.

extensions/renderer/resources/runtime_custom_bindings.js

 // Copyright 2014 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 runtime API.
 
 var binding = require('binding').Binding.create('runtime');
 
 var messaging = require('messaging');
 var runtimeNatives = requireNative('runtime');
 var process = requireNative('process');
 var utils = require('utils');
 
-var backgroundPage = window;
+var WINDOW = {};
+try {
+  WINDOW = window;
+} catch (e) {
+  // Running in SW context.
+  // TODO(lazyboy): Synchronous access to background page is not possible from
+  // service worker context. Decide what we should do in this case for the class
+  // of APIs that require access to background page or window object
+}
+
+var backgroundPage = WINDOW;
 var backgroundRequire = require;
 var contextType = process.GetContextType();
 
 if (contextType == 'BLESSED_EXTENSION' ||
     contextType == 'UNBLESSED_EXTENSION') {
   var manifest = runtimeNatives.GetManifest();
   if (manifest.app && manifest.app.background) {
     // Get the background page if one exists. Otherwise, default to the current
     // window.
     backgroundPage = runtimeNatives.GetExtensionViews(-1, 'BACKGROUND')[0];
     if (backgroundPage) {
       var GetModuleSystem = requireNative('v8_context').GetModuleSystem;
       backgroundRequire = GetModuleSystem(backgroundPage).require;
     } else {
-      backgroundPage = window;
+      backgroundPage = WINDOW;
     }
   }
 }
 
 // For packaged apps, all windows use the bindFileEntryCallback from the
 // background page so their FileEntry objects have the background page's context
 // as their own.  This allows them to be used from other windows (including the
 // background page) after the original window is closed.
-if (window == backgroundPage) {
+if (WINDOW == backgroundPage) {
   var lastError = require('lastError');
   var fileSystemNatives = requireNative('file_system_natives');
   var GetIsolatedFileSystem = fileSystemNatives.GetIsolatedFileSystem;
   var bindDirectoryEntryCallback = function(functionName, apiFunctions) {
     apiFunctions.setCustomCallback(functionName,
         function(name, request, callback, response) {
       if (callback) {
         if (!response) {
           callback();
           return;
@@ skipping 121 matching lines @@
       var bg = runtimeNatives.GetExtensionViews(-1, 'BACKGROUND')[0] || null;
       callback(bg);
     }
   });
 
   bindDirectoryEntryCallback('getPackageDirectoryEntry', apiFunctions);
 });
 
 exports.$set('bindDirectoryEntryCallback', bindDirectoryEntryCallback);
 exports.$set('binding', binding.generate());