Clean up header files.

BUG=138542
[email protected]
NOPRESUBMIT=true

Review URL: https://codereview.chromium.org/1544283002

Cr-Commit-Position: refs/heads/master@{#366903}
diff --git a/sql/connection.cc b/sql/connection.cc
index 88acef0..4d23f7df 100644
--- a/sql/connection.cc
+++ b/sql/connection.cc
@@ -4,6 +4,7 @@
 
 #include "sql/connection.h"
 
+#include <limits.h>
 #include <stddef.h>
 #include <stdint.h>
 #include <string.h>