Take extensions out of Profile into a profile-keyed service, ExtensionSystem.

chrome/browser/extensions/extension_message_handler.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/browser/extensions/extension_message_handler.h"
 
 #include "chrome/browser/extensions/extension_message_service.h"
+#include "chrome/browser/extensions/extension_system.h"
+#include "chrome/browser/extensions/extension_system_factory.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/extensions/extension_messages.h"
 #include "content/browser/renderer_host/render_view_host.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/render_view_host_delegate.h"
 
 ExtensionMessageHandler::ExtensionMessageHandler(
     RenderViewHost* render_view_host)
     : content::RenderViewHostObserver(render_view_host) {
 }
@@ skipping 13 matching lines @@
 
 void ExtensionMessageHandler::RenderViewHostInitialized() {
   Send(new ExtensionMsg_NotifyRenderViewType(
       routing_id(), render_view_host()->delegate()->GetRenderViewType()));
 }
 
 void ExtensionMessageHandler::OnPostMessage(int port_id,
                                             const std::string& message) {
   Profile* profile = Profile::FromBrowserContext(
       render_view_host()->process()->GetBrowserContext());
-  if (profile->GetExtensionMessageService()) {
-    profile->GetExtensionMessageService()->PostMessageFromRenderer(
-        port_id, message);
+  ExtensionMessageService* message_service =
+      ExtensionSystemFactory::GetForProfile(profile)->message_service();
+  if (message_service) {
+    message_service->PostMessageFromRenderer(port_id, message);
   }
 }