chrome: Cleanup class/struct forward declarations

chrome/browser/extensions/activity_log/activity_database.h

 // Copyright (c) 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 CHROME_BROWSER_EXTENSIONS_ACTIVITY_LOG_ACTIVITY_DATABASE_H_
 #define CHROME_BROWSER_EXTENSIONS_ACTIVITY_LOG_ACTIVITY_DATABASE_H_
 
 #include <string>
 #include <vector>
 
 #include "base/files/file_path.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/synchronization/lock.h"
 #include "base/timer/timer.h"
 #include "chrome/browser/extensions/activity_log/activity_actions.h"
 #include "extensions/common/extension.h"
 #include "sql/connection.h"
 
 namespace base {
-class Clock;
 class FilePath;
 }
 
 namespace extensions {
 
 // Encapsulates the SQL connection for the activity log database.  This class
 // holds the database connection and has methods for writing.  All of the
 // methods except the constructor need to be called on the DB thread.
 //
 // Object ownership and lifetime is a bit complicated for ActivityLog,
@@ skipping 162 matching lines @@
   friend class ActivityLogDatabasePolicy;
   FRIEND_TEST_ALL_PREFIXES(ActivityDatabaseTest, BatchModeOff);
   FRIEND_TEST_ALL_PREFIXES(ActivityDatabaseTest, BatchModeOn);
   FRIEND_TEST_ALL_PREFIXES(ActivityDatabaseTest, BatchModeFlush);
   DISALLOW_COPY_AND_ASSIGN(ActivityDatabase);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_ACTIVITY_LOG_ACTIVITY_DATABASE_H_