Update some uses of char16 to use the base:: namespace.

url/url_test_utils.h

Index: url/url_test_utils.h
diff --git a/url/url_test_utils.h b/url/url_test_utils.h
index 6efdeea106073e1690921448122c5ecf106c143d..64b4acbeaf33b1b2703838082fdf1958fbcd61c1 100644
--- a/url/url_test_utils.h
+++ b/url/url_test_utils.h
@@ -23,7 +23,7 @@ inline base::string16 WStringToUTF16(const wchar_t* src) {
   base::string16 str;
   int length = static_cast<int>(wcslen(src));
   for (int i = 0; i < length; ++i) {
-    str.push_back(static_cast<char16>(src[i]));
+    str.push_back(static_cast<base::char16>(src[i]));
   }
   return str;
 }