Cleanup remaining class/struct fwd declarations

cc/output/in_process_context_provider.h

 // Copyright 2016 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 CC_OUTPUT_IN_PROCESS_CONTEXT_PROVIDER_H_
 #define CC_OUTPUT_IN_PROCESS_CONTEXT_PROVIDER_H_
 
 #include <stdint.h>
 
 #include <memory>
 
 #include "base/compiler_specific.h"
 #include "base/synchronization/lock.h"
 #include "cc/base/cc_export.h"
 #include "cc/output/context_cache_controller.h"
 #include "cc/output/context_provider.h"
 #include "gpu/command_buffer/common/gles2_cmd_utils.h"
 #include "gpu/ipc/in_process_command_buffer.h"
 #include "ui/gfx/native_widget_types.h"
 
 class GrContext;
 
 namespace gpu {
 class GLInProcessContext;
 class GpuMemoryBufferManager;
 class ImageFactory;
 struct SharedMemoryLimits;
-class SyncPointManager;
-namespace gles2 {
-class MailboxManager;
-}
 }
 
 namespace skia_bindings {
 class GrContextForGLES2Interface;
 }
 
 namespace cc {
 
 class CC_EXPORT InProcessContextProvider
     : public NON_EXPORTED_BASE(ContextProvider) {
@@ skipping 36 matching lines @@
 
   base::Lock context_lock_;
   std::unique_ptr<gpu::GLInProcessContext> context_;
   std::unique_ptr<skia_bindings::GrContextForGLES2Interface> gr_context_;
   std::unique_ptr<ContextCacheController> cache_controller_;
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_IN_PROCESS_CONTEXT_PROVIDER_H_