content: Cleanup class/struct forward declarations

content/renderer/render_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_RENDERER_RENDER_THREAD_IMPL_H_
 #define CONTENT_RENDERER_RENDER_THREAD_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 52 matching lines @@
 class WebMediaStreamCenterClient;
 }
 
 namespace base {
 class SingleThreadTaskRunner;
 class Thread;
 }
 
 namespace cc {
 class BeginFrameSource;
-class ContextProvider;
 class ImageSerializationProcessor;
 class CompositorFrameSink;
 class TaskGraphRunner;
 }
 
 namespace gpu {
 class GpuChannelHost;
 }
 
 namespace IPC {
@@ skipping 25 matching lines @@
 class ChildGpuMemoryBufferManager;
 class CompositorForwardingMessageFilter;
 class ContextProviderCommandBuffer;
 class DBMessageFilter;
 class DevToolsAgentFilter;
 class DomStorageDispatcher;
 class EmbeddedWorkerDispatcher;
 class FrameSwapMessageQueue;
 class IndexedDBDispatcher;
 class InputHandlerManager;
-class MediaStreamCenter;
 class MemoryObserver;
 class MidiMessageFilter;
 class P2PSocketDispatcher;
 class PeerConnectionDependencyFactory;
 class PeerConnectionTracker;
 class CategorizedWorkerPool;
 class RenderThreadObserver;
 class RendererBlinkPlatformImpl;
 class RendererGpuVideoAcceleratorFactories;
 class ResourceDispatchThrottler;
@@ skipping 620 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(RenderThreadImpl);
 };
 
 #if defined(COMPILER_MSVC)
 #pragma warning(pop)
 #endif
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_RENDER_THREAD_IMPL_H_