Convert JsonWriter::Write to taking a const ref for the in-param

chromeos/network/onc/onc_translator_onc_to_shill.cc

Index: chromeos/network/onc/onc_translator_onc_to_shill.cc
diff --git a/chromeos/network/onc/onc_translator_onc_to_shill.cc b/chromeos/network/onc/onc_translator_onc_to_shill.cc
index 9cea03314c35f060a6d04cbc0f75ca4f11f50ed3..33b9e8d5becb17e629462f34bcb16a6604de0159 100644
--- a/chromeos/network/onc/onc_translator_onc_to_shill.cc
+++ b/chromeos/network/onc/onc_translator_onc_to_shill.cc
@@ -31,7 +31,7 @@ namespace {
 scoped_ptr<base::StringValue> ConvertValueToString(const base::Value& value) {
   std::string str;
   if (!value.GetAsString(&str))
-    base::JSONWriter::Write(&value, &str);
+    base::JSONWriter::Write(value, &str);
   return make_scoped_ptr(new base::StringValue(str));
 }