gpu: Cleanup class/struct forward declarations

gpu/command_buffer/common/command_buffer.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 GPU_COMMAND_BUFFER_COMMON_COMMAND_BUFFER_H_
 #define GPU_COMMAND_BUFFER_COMMON_COMMAND_BUFFER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "base/macros.h"
 #include "gpu/command_buffer/common/buffer.h"
 #include "gpu/command_buffer/common/constants.h"
 #include "gpu/gpu_export.h"
 
-namespace base {
-class SharedMemory;
-}
-
 namespace gpu {
 
 // Common interface for CommandBuffer implementations.
 class GPU_EXPORT CommandBuffer {
  public:
   struct State {
     State()
         : get_offset(0),
           token(-1),
           error(error::kNoError),
@@ skipping 97 matching lines @@
   virtual error::Error GetLastError();
 #endif
 
  private:
   DISALLOW_COPY_AND_ASSIGN(CommandBuffer);
 };
 
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_COMMON_COMMAND_BUFFER_H_