Revert of Fix (or tag) uses of explicit '64' instead of GL_MAILBOX_SIZE_CHROMIUM

gpu/command_buffer/service/mailbox_manager.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_SERVICE_MAILBOX_MANAGER_H_
 #define GPU_COMMAND_BUFFER_SERVICE_MAILBOX_MANAGER_H_
 
 #include <functional>
 #include <map>
 
 #include "base/memory/linked_ptr.h"
 #include "base/memory/ref_counted.h"
 #include "gpu/command_buffer/common/constants.h"
 #include "gpu/command_buffer/common/mailbox.h"
 #include "gpu/gpu_export.h"
 
+// From gl2/gl2ext.h.
+#ifndef GL_MAILBOX_SIZE_CHROMIUM
+#define GL_MAILBOX_SIZE_CHROMIUM 64
+#endif
+
 typedef signed char GLbyte;
 
 namespace gpu {
 namespace gles2 {
 
 class Texture;
 class TextureManager;
 
 // Manages resources scoped beyond the context or context group level.
 class GPU_EXPORT MailboxManager : public base::RefCounted<MailboxManager> {
@@ skipping 41 matching lines @@
   MailboxToTextureMap mailbox_to_textures_;
   TextureToMailboxMap textures_to_mailboxes_;
 
   DISALLOW_COPY_AND_ASSIGN(MailboxManager);
 };
 }  // namespage gles2
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_SERVICE_MAILBOX_MANAGER_H_