command_buffer: Remove hash_tables.h, simplify atomicops.h

gpu/command_buffer/client/atomicops.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_CLIENT_ATOMICOPS_H_
 #define GPU_COMMAND_BUFFER_CLIENT_ATOMICOPS_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "gpu/command_buffer/common/types.h"
 #include "gpu/gpu_export.h"
 
 namespace gpu {
 
-GPU_EXPORT void MemoryBarrier();
-
 class LockImpl;
 class GPU_EXPORT Lock {
  public:
   Lock();
   ~Lock();
   void Acquire();
   void Release();
   bool Try();
   void AssertAcquired() const;
 
@@ skipping 16 matching lines @@
   }
 
  private:
   Lock& lock_;
   DISALLOW_COPY_AND_ASSIGN(AutoLock);
 };
 
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_CLIENT_ATOMICOPS_H_