content: Cleanup class/struct forward declarations

content/utility/utility_thread_impl.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 CONTENT_UTILITY_UTILITY_THREAD_IMPL_H_
 #define CONTENT_UTILITY_UTILITY_THREAD_IMPL_H_
 
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "build/build_config.h"
 #include "content/child/child_thread_impl.h"
 #include "content/common/content_export.h"
 #include "content/public/utility/utility_thread.h"
 #include "mojo/public/cpp/bindings/binding_set.h"
 #include "services/service_manager/public/interfaces/service_factory.mojom.h"
 
 namespace content {
-class BlinkPlatformImpl;
 class UtilityBlinkPlatformImpl;
 class UtilityServiceFactory;
 
 #if defined(COMPILER_MSVC)
 // See explanation for other RenderViewHostImpl which is the same issue.
 #pragma warning(push)
 #pragma warning(disable: 4250)
 #endif
 
 // This class represents the background thread where the utility task runs.
@@ skipping 38 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(UtilityThreadImpl);
 };
 
 #if defined(COMPILER_MSVC)
 #pragma warning(pop)
 #endif
 
 }  // namespace content
 
 #endif  // CONTENT_UTILITY_UTILITY_THREAD_IMPL_H_