Remove dead ntp_tiles thumbnail-related code.

components/ntp_tiles/most_visited_sites.h

 // Copyright 2013 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 COMPONENTS_NTP_TILES_MOST_VISITED_SITES_H_
 #define COMPONENTS_NTP_TILES_MOST_VISITED_SITES_H_
 
 #include <stddef.h>
 
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/files/file_path.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/scoped_observer.h"
 #include "components/history/core/browser/history_types.h"
 #include "components/history/core/browser/top_sites_observer.h"
 #include "components/ntp_tiles/popular_sites.h"
 #include "components/suggestions/proto/suggestions.pb.h"
 #include "components/suggestions/suggestions_service.h"
 #include "url/gurl.h"
 
-namespace gfx {
-class Image;
-}
-
 namespace history {
 class TopSites;
 }
 
 namespace suggestions {
 class SuggestionsService;
 }
 
 namespace user_prefs {
 class PrefRegistrySyncable;
@@ skipping 99 matching lines @@
                    scoped_refptr<history::TopSites> top_sites,
                    suggestions::SuggestionsService* suggestions,
                    MostVisitedSitesSupervisor* supervisor);
 
   ~MostVisitedSites() override;
 
   // Does not take ownership of |observer|, which must outlive this object and
   // must not be null.
   void SetMostVisitedURLsObserver(Observer* observer, int num_sites);
 
-  using ThumbnailCallback = base::Callback<
-      void(bool /* is_local_thumbnail */, const SkBitmap* /* bitmap */)>;
   void AddOrRemoveBlacklistedUrl(const GURL& url, bool add_url);
   void RecordTileTypeMetrics(const std::vector<int>& tile_types);
   void RecordOpenedMostVisitedItem(int index, int tile_type);
 
   // MostVisitedSitesSupervisor::Observer implementation.
   void OnBlockedSitesChanged() override;
 
   static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
 
  private:
@@ skipping 101 matching lines @@
 
   // For callbacks may be run after destruction.
   base::WeakPtrFactory<MostVisitedSites> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MostVisitedSites);
 };
 
 }  // namespace ntp_tiles
 
 #endif  // COMPONENTS_NTP_TILES_MOST_VISITED_SITES_H_