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

gpu/command_buffer/common/mailbox.h

Index: gpu/command_buffer/common/mailbox.h
diff --git a/gpu/command_buffer/common/mailbox.h b/gpu/command_buffer/common/mailbox.h
index 08a970fad856c06221f1db2acd7ac04e0d0de58f..d9d25d418d3eeb0c6843809c98092f76bf39ecee 100644
--- a/gpu/command_buffer/common/mailbox.h
+++ b/gpu/command_buffer/common/mailbox.h
@@ -10,11 +10,6 @@
 #include "gpu/command_buffer/common/types.h"
 #include "gpu/gpu_export.h"
 
-// From gl2/gl2ext.h.
-#ifndef GL_MAILBOX_SIZE_CHROMIUM
-#define GL_MAILBOX_SIZE_CHROMIUM 64
-#endif
-
 namespace gpu {
 
 struct GPU_EXPORT Mailbox {
@@ -22,7 +17,7 @@
   bool IsZero() const;
   void SetZero();
   void SetName(const int8* name);
-  int8 name[GL_MAILBOX_SIZE_CHROMIUM];
+  int8 name[64];
   bool operator<(const Mailbox& other) const {
     return memcmp(this, &other, sizeof other) < 0;
   }