Split ExtensionSystem interface from ExtensionSystemImpl implementation, part 1.

chrome/browser/extensions/navigation_observer.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/navigation_observer.h"
 
 #include "chrome/browser/extensions/extension_install_ui.h"
 #include "chrome/browser/extensions/extension_service.h"
-#include "chrome/browser/extensions/extension_system.h"
 #include "chrome/browser/profiles/profile.h"
 #include "content/public/browser/navigation_controller.h"
 #include "content/public/browser/navigation_entry.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/notification_types.h"
+#include "extensions/browser/extension_system.h"
 
 using content::NavigationController;
 using content::NavigationEntry;
 
 namespace extensions {
 
 NavigationObserver::NavigationObserver(Profile* profile) : profile_(profile) {
   RegisterForNotifications();
 }
 
@@ skipping 86 matching lines @@
   extension_install_prompt_.reset();
 
   std::string histogram_name = user_initiated ?
       "Extensions.Permissions_ReEnableCancel" :
       "Extensions.Permissions_ReEnableAbort";
   ExtensionService::RecordPermissionMessagesHistogram(
       extension, histogram_name.c_str());
 }
 
 }  // namespace extensions