Re-land alexbost's experimental offscreenTabs API.

chrome/renderer/extensions/extension_dispatcher.cc

 // 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.
 
 #include "chrome/renderer/extensions/extension_dispatcher.h"
 
 #include "base/callback.h"
 #include "base/command_line.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/string_piece.h"
@@ skipping 460 matching lines @@
                              IDR_BROWSER_ACTION_CUSTOM_BINDINGS_JS);
   source_map_.RegisterSource("chromePrivate",
                              IDR_CHROME_PRIVATE_CUSTOM_BINDINGS_JS);
   source_map_.RegisterSource("contentSettings",
                              IDR_CONTENT_SETTINGS_CUSTOM_BINDINGS_JS);
   source_map_.RegisterSource("contextMenus",
                              IDR_CONTEXT_MENUS_CUSTOM_BINDINGS_JS);
   source_map_.RegisterSource("devtools", IDR_DEVTOOLS_CUSTOM_BINDINGS_JS);
   source_map_.RegisterSource("experimental.declarative",
                              IDR_EXPERIMENTAL_DECLARATIVE_CUSTOM_BINDINGS_JS);
+  source_map_.RegisterSource("experimental.offscreen",
+                             IDR_EXPERIMENTAL_OFFSCREENTABS_CUSTOM_BINDINGS_JS);
   source_map_.RegisterSource("experimental.socket",
                              IDR_EXPERIMENTAL_SOCKET_CUSTOM_BINDINGS_JS);
   source_map_.RegisterSource("extension", IDR_EXTENSION_CUSTOM_BINDINGS_JS);
   source_map_.RegisterSource("fileBrowserHandler",
                              IDR_FILE_BROWSER_HANDLER_CUSTOM_BINDINGS_JS);
   source_map_.RegisterSource("fileBrowserPrivate",
                              IDR_FILE_BROWSER_PRIVATE_CUSTOM_BINDINGS_JS);
   source_map_.RegisterSource("i18n", IDR_I18N_CUSTOM_BINDINGS_JS);
   source_map_.RegisterSource("input.ime", IDR_INPUT_IME_CUSTOM_BINDINGS_JS);
   source_map_.RegisterSource("omnibox", IDR_OMNIBOX_CUSTOM_BINDINGS_JS);
@@ skipping 236 matching lines @@
   webrequest_adblock_ = adblock;
   webrequest_adblock_plus_ = adblock_plus;
   webrequest_other_ = other;
 }
 
 void ExtensionDispatcher::OnShouldClose(const std::string& extension_id,
                                         int sequence_id) {
   RenderThread::Get()->Send(
       new ExtensionHostMsg_ShouldCloseAck(extension_id, sequence_id));
 }