Code cleanup

chrome/browser/history/history_backend.h

 // 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.
 
 #ifndef CHROME_BROWSER_HISTORY_HISTORY_BACKEND_H_
 #define CHROME_BROWSER_HISTORY_HISTORY_BACKEND_H_
 
 #include <set>
 #include <string>
 #include <utility>
@@ skipping 20 matching lines @@
 #endif
 
 class HistoryURLProvider;
 struct HistoryURLProviderParams;
 struct ImportedFaviconUsage;
 class TestingProfile;
 struct ThumbnailScore;
 
 namespace base {
 class MessageLoop;
+class SingleThreadTaskRunner;
 }
 
 namespace history {
 #if defined(OS_ANDROID)
 class AndroidProviderBackend;
 #endif
 
 class CommitLaterTask;
 struct DownloadRow;
 class HistoryClient;
 class HistoryDBTask;
 class InMemoryHistoryBackend;
+class TypedUrlSyncableService;
 class VisitFilter;
-class TypedUrlSyncableService;
 
 // The maximum number of icons URLs per page which can be stored in the
 // thumbnail database.
 static const size_t kMaxFaviconsPerPage = 8;
 
 // The maximum number of bitmaps for a single icon URL which can be stored in
 // the thumbnail database.
 static const size_t kMaxFaviconBitmapsPerIconURL = 8;
 
 class QueuedHistoryDBTask {
@@ skipping 831 matching lines @@
 
   // Listens for the system being under memory pressure.
   scoped_ptr<base::MemoryPressureListener> memory_pressure_listener_;
 
   DISALLOW_COPY_AND_ASSIGN(HistoryBackend);
 };
 
 }  // namespace history
 
 #endif  // CHROME_BROWSER_HISTORY_HISTORY_BACKEND_H_