cc: Cleanup class/struct forward declarations

cc/raster/staging_buffer_pool.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_RASTER_STAGING_BUFFER_POOL_H_
 #define CC_RASTER_STAGING_BUFFER_POOL_H_
 
 #include <stdint.h>
 
 #include <deque>
@@ skipping 11 matching lines @@
 #include "cc/resources/resource_provider.h"
 
 namespace gpu {
 namespace gles2 {
 class GLES2Interface;
 }
 }
 
 namespace cc {
 class Resource;
-class RasterSource;
-class ResourcePool;
 
 struct StagingBuffer {
   StagingBuffer(const gfx::Size& size, ResourceFormat format);
   ~StagingBuffer();
 
   void DestroyGLResources(gpu::gles2::GLES2Interface* gl);
   void OnMemoryDump(base::trace_event::ProcessMemoryDump* pmd,
                     ResourceFormat format,
                     bool is_free) const;
 
@@ skipping 70 matching lines @@
   base::Closure reduce_memory_usage_callback_;
 
   base::WeakPtrFactory<StagingBufferPool> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(StagingBufferPool);
 };
 
 }  // namespace cc
 
 #endif  // CC_RASTER_STAGING_BUFFER_POOL_H_