Switch to standard integer types in net/.

BUG=488550
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Review URL: https://codereview.chromium.org/1535363003 .

Cr-Commit-Position: refs/heads/master@{#366297}
diff --git a/net/proxy/multi_threaded_proxy_resolver.h b/net/proxy/multi_threaded_proxy_resolver.h
index 30a7b1b..f00249f 100644
--- a/net/proxy/multi_threaded_proxy_resolver.h
+++ b/net/proxy/multi_threaded_proxy_resolver.h
@@ -5,9 +5,10 @@
 #ifndef NET_PROXY_MULTI_THREADED_PROXY_RESOLVER_H_
 #define NET_PROXY_MULTI_THREADED_PROXY_RESOLVER_H_
 
+#include <stddef.h>
+
 #include <set>
 
-#include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "net/base/net_export.h"