Switch to standard integer types in ui/gfx/.

BUG=138542
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Review URL: https://codereview.chromium.org/1543183002

Cr-Commit-Position: refs/heads/master@{#366731}
diff --git a/ui/gfx/transform_util_unittest.cc b/ui/gfx/transform_util_unittest.cc
index 76847a67..907f8a8 100644
--- a/ui/gfx/transform_util_unittest.cc
+++ b/ui/gfx/transform_util_unittest.cc
@@ -4,6 +4,8 @@
 
 #include "ui/gfx/transform_util.h"
 
+#include <stddef.h>
+
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/geometry/point.h"
 #include "ui/gfx/geometry/point3_f.h"