Cleanup: Remove unneeded forward declarations from various chrome subdirectories.

chrome/service/cloud_print/cloud_print_proxy_backend.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_SERVICE_CLOUD_PRINT_CLOUD_PRINT_PROXY_BACKEND_H_
 #define CHROME_SERVICE_CLOUD_PRINT_CLOUD_PRINT_PROXY_BACKEND_H_
 #pragma once
 
 #include <string>
 
 #include "base/threading/thread.h"
 #include "printing/backend/print_backend.h"
 
-class CloudPrintProxyService;
 class GURL;
 
 namespace base {
 class DictionaryValue;
 }
 
 namespace gaia {
 struct OAuthClientInfo;
 }
 
@@ skipping 78 matching lines @@
   MessageLoop* const frontend_loop_;
   // The frontend which is responsible for displaying UI and updating Prefs
   CloudPrintProxyFrontend* frontend_;
 
   friend class base::RefCountedThreadSafe<CloudPrintProxyBackend::Core>;
 
   DISALLOW_COPY_AND_ASSIGN(CloudPrintProxyBackend);
 };
 
 #endif  // CHROME_SERVICE_CLOUD_PRINT_CLOUD_PRINT_PROXY_BACKEND_H_