remoting: Cleanup class/struct fwd declarations

remoting/test/app_remoting_connection_helper.h

 // Copyright 2015 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 REMOTING_TEST_APP_REMOTING_CONNECTION_HELPER_H_
 #define REMOTING_TEST_APP_REMOTING_CONNECTION_HELPER_H_
 
 #include <memory>
 #include <string>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/threading/thread_checker.h"
 #include "remoting/test/remote_connection_observer.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
 class RunLoop;
 class Timer;
-class Lock;
 }
 
 namespace remoting {
 namespace test {
 
 struct RemoteApplicationDetails;
 class TestChromotingClient;
 
 // Creates a connection to a remote host which is available for tests to use.
 // A TestChromotingClient is required from caller.
@@ skipping 56 matching lines @@
   // Creates and manages the connection to the remote host.
   std::unique_ptr<TestChromotingClient> client_;
 
   DISALLOW_COPY_AND_ASSIGN(AppRemotingConnectionHelper);
 };
 
 }  // namespace test
 }  // namespace remoting
 
 #endif  // REMOTING_TEST_APP_REMOTING_CONNECTION_HELPER_H_