Extract LazyBackgroundTaskQueue from ExtensionSystem.

extensions/browser/guest_view/app_view/app_view_guest.cc

 // 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.
 
 #include "extensions/browser/guest_view/app_view/app_view_guest.h"
 
 #include "base/command_line.h"
 #include "components/guest_view/browser/guest_view_manager.h"
 #include "content/public/browser/render_view_host.h"
 #include "content/public/common/renderer_preferences.h"
@@ skipping 189 matching lines @@
   }
 
   pending_response_map.Get().insert(
       std::make_pair(guest_instance_id(),
                      make_linked_ptr(new ResponseInfo(
                                         guest_extension,
                                         weak_ptr_factory_.GetWeakPtr(),
                                         callback))));
 
   LazyBackgroundTaskQueue* queue =
-      ExtensionSystem::Get(browser_context())->lazy_background_task_queue();
+      LazyBackgroundTaskQueue::Get(browser_context());
   if (queue->ShouldEnqueueTask(browser_context(), guest_extension)) {
     queue->AddPendingTask(browser_context(),
                           guest_extension->id(),
                           base::Bind(
                               &AppViewGuest::LaunchAppAndFireEvent,
                               weak_ptr_factory_.GetWeakPtr(),
                               base::Passed(make_scoped_ptr(data->DeepCopy())),
                               callback));
     return;
   }
@@ skipping 67 matching lines @@
   embed_request->Set(appview::kData, data.release());
   AppRuntimeEventRouter::DispatchOnEmbedRequestedEvent(
       browser_context(), embed_request.Pass(), extension_host->extension());
 }
 
 void AppViewGuest::SetAppDelegateForTest(AppDelegate* delegate) {
   app_delegate_.reset(delegate);
 }
 
 }  // namespace extensions