Get rid of the relative paths in command_buffer client/common

gpu/command_buffer/common/mailbox.cc

Index: gpu/command_buffer/common/mailbox.cc
===================================================================
--- gpu/command_buffer/common/mailbox.cc	(revision 201875)
+++ gpu/command_buffer/common/mailbox.cc	(working copy)
@@ -2,11 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "../common/mailbox.h"
+#include "gpu/command_buffer/common/mailbox.h"
 
 #include <string.h>
 
-#include "../common/logging.h"
+#include "gpu/command_buffer/common/logging.h"
 
 namespace gpu {