Cleanup: Remove forward declarations in various chrome/browser directories.

chrome/browser/history/history_database.h

 // Copyright (c) 2011 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_DATABASE_H_
 #define CHROME_BROWSER_HISTORY_HISTORY_DATABASE_H_
 #pragma once
 
 #include "base/gtest_prod_util.h"
 #include "build/build_config.h"
 #include "chrome/browser/history/download_database.h"
 #include "chrome/browser/history/history_types.h"
 #include "chrome/browser/history/starred_url_database.h"
 #include "chrome/browser/history/url_database.h"
 #include "chrome/browser/history/visit_database.h"
 #include "chrome/browser/history/visitsegment_database.h"
 #include "sql/connection.h"
 #include "sql/init_status.h"
 #include "sql/meta_table.h"
 
 class FilePath;
 
 namespace history {
 
-// Forward declaration for the temporary migration code in Init().
-class TextDatabaseManager;
-
 // Encapsulates the SQL connection for the history database. This class holds
 // the database connection and has methods the history system (including full
 // text search) uses for writing and retrieving information.
 //
 // We try to keep most logic out of the history database; this should be seen
 // as the storage interface. Logic for manipulating this storage layer should
 // be in HistoryBackend.cc.
 class HistoryDatabase : public DownloadDatabase,
   // TODO(sky): See if we can nuke StarredURLDatabase and just create on the
   // stack for migration. Then HistoryDatabase would directly descend from
@@ skipping 136 matching lines @@
   sql::MetaTable meta_table_;
 
   base::Time cached_early_expiration_threshold_;
 
   // See the getters above.
   bool needs_version_17_migration_;
 
   DISALLOW_COPY_AND_ASSIGN(HistoryDatabase);
 };
 
-}  // history
+}  // namespace history
 
 #endif  // CHROME_BROWSER_HISTORY_HISTORY_DATABASE_H_