content: Cleanup class/struct forward declarations

content/browser/compositor/gpu_process_transport_factory.h

 // Copyright 2014 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_BROWSER_COMPOSITOR_GPU_PROCESS_TRANSPORT_FACTORY_H_
 #define CONTENT_BROWSER_COMPOSITOR_GPU_PROCESS_TRANSPORT_FACTORY_H_
 
 #include <stdint.h>
 
 #include <map>
 #include <memory>
 
 #include "base/id_map.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "build/build_config.h"
 #include "content/browser/compositor/image_transport_factory.h"
 #include "gpu/ipc/client/gpu_channel_host.h"
 #include "ui/compositor/compositor.h"
 
-namespace base {
-class Thread;
-}
-
 namespace cc {
 class SingleThreadTaskGraphRunner;
 class SoftwareOutputDevice;
 class SurfaceManager;
 class VulkanInProcessContextProvider;
 }
 
 namespace content {
 class ContextProviderCommandBuffer;
 class OutputDeviceBacking;
@@ skipping 89 matching lines @@
   gpu::GpuChannelEstablishFactory* gpu_channel_factory_ = nullptr;
 
   base::WeakPtrFactory<GpuProcessTransportFactory> callback_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(GpuProcessTransportFactory);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_COMPOSITOR_GPU_PROCESS_TRANSPORT_FACTORY_H_