Remove TopSites::IsEnabled() as well as related dead code.

chrome/browser/dom_ui/dom_ui_thumbnail_source.h

 // Copyright (c) 2010 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.
 
 #ifndef CHROME_BROWSER_DOM_UI_DOM_UI_THUMBNAIL_SOURCE_H_
 #define CHROME_BROWSER_DOM_UI_DOM_UI_THUMBNAIL_SOURCE_H_
 #pragma once
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/ref_counted.h"
+#include "base/ref_counted_memory.h"
 #include "chrome/browser/dom_ui/chrome_url_data_manager.h"
-#include "chrome/browser/history/history.h"
-#include "chrome/common/notification_registrar.h"
 
 class Profile;
 
 namespace history {
 class TopSites;
 }
 
 // ThumbnailSource is the gateway between network-level chrome: requests for
 // thumbnails and the history/top-sites backend that serves these.
 class DOMUIThumbnailSource : public ChromeURLDataManager::DataSource {
  public:
   explicit DOMUIThumbnailSource(Profile* profile);
 
   // Called when the network layer has requested a resource underneath
   // the path we registered.
   virtual void StartDataRequest(const std::string& path,
                                 bool is_off_the_record,
                                 int request_id);
 
   virtual std::string GetMimeType(const std::string& path) const;
 
   virtual MessageLoop* MessageLoopForRequestPath(const std::string& path) const;
 
-  // Called when thumbnail data is available from the history backend.
-  void OnThumbnailDataAvailable(HistoryService::Handle request_handle,
-                                scoped_refptr<RefCountedBytes> data);
-
  private:
   virtual ~DOMUIThumbnailSource();
 
   // Send the default thumbnail when we are missing a real one.
   void SendDefaultThumbnail(int request_id);
 
   Profile* profile_;
 
-  CancelableRequestConsumerT<int, 0> cancelable_consumer_;
-
   // Raw PNG representation of the thumbnail to show when the thumbnail
   // database doesn't have a thumbnail for a webpage.
   scoped_refptr<RefCountedMemory> default_thumbnail_;
 
-  // TopSites. If non-null we're using TopSites.
+  // TopSites.
   scoped_refptr<history::TopSites> top_sites_;
 
   DISALLOW_COPY_AND_ASSIGN(DOMUIThumbnailSource);
 };
 
 #endif  // CHROME_BROWSER_DOM_UI_DOM_UI_THUMBNAIL_SOURCE_H_