Revert of Added SyncToken command buffer trait to help with IPC messages.

gpu/command_buffer/service/mailbox_manager.h

 // Copyright 2014 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_SERVICE_MAILBOX_MANAGER_H_
 #define GPU_COMMAND_BUFFER_SERVICE_MAILBOX_MANAGER_H_
 
 #include "base/memory/ref_counted.h"
 #include "gpu/command_buffer/common/mailbox.h"
 #include "gpu/gpu_export.h"
 
 namespace gpu {
-
-struct SyncToken;
-
 namespace gles2 {
 
 class Texture;
+struct SyncToken;
 
 // Manages resources scoped beyond the context or context group level.
 class GPU_EXPORT MailboxManager : public base::RefCounted<MailboxManager> {
  public:
   static scoped_refptr<MailboxManager> Create();
 
   // Look up the texture definition from the named mailbox.
   virtual Texture* ConsumeTexture(const Mailbox& mailbox) = 0;
 
   // Put the texture into the named mailbox.
@@ skipping 17 matching lines @@
   friend class base::RefCounted<MailboxManager>;
 
   DISALLOW_COPY_AND_ASSIGN(MailboxManager);
 };
 
 }  // namespage gles2
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_SERVICE_MAILBOX_MANAGER_H_