chrome: Cleanup class/struct forward declarations

chrome/browser/sessions/session_service_test_helper.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_SESSIONS_SESSION_SERVICE_TEST_HELPER_H_
 #define CHROME_BROWSER_SESSIONS_SESSION_SERVICE_TEST_HELPER_H_
 
 #include <stddef.h>
 
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
 #include "components/sessions/core/session_id.h"
 
 class SessionService;
 
-namespace base {
-class RunLoop;
-}
-
 namespace sessions {
 class SerializedNavigationEntry;
-class SessionCommand;
 struct SessionTab;
 struct SessionWindow;
 }
 
 // A simple class that makes writing SessionService related tests easier.
 
 class SessionServiceTestHelper {
  public:
   SessionServiceTestHelper();
   explicit SessionServiceTestHelper(SessionService* service);
@@ skipping 47 matching lines @@
   void RunTaskOnBackendThread(const tracked_objects::Location& from_here,
                               const base::Closure& task);
 
  private:
   std::unique_ptr<SessionService> service_;
 
   DISALLOW_COPY_AND_ASSIGN(SessionServiceTestHelper);
 };
 
 #endif  // CHROME_BROWSER_SESSIONS_SESSION_SERVICE_TEST_HELPER_H_