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

chrome/browser/extensions/extension_messages_apitest.cc

Index: chrome/browser/extensions/extension_messages_apitest.cc
diff --git a/chrome/browser/extensions/extension_messages_apitest.cc b/chrome/browser/extensions/extension_messages_apitest.cc
index 1c430525767a19fc48f29fe444ca8e4da938ac36..9edda300b03e7b5ed5db2ea72b1b023c3c1ee341 100644
--- a/chrome/browser/extensions/extension_messages_apitest.cc
+++ b/chrome/browser/extensions/extension_messages_apitest.cc
@@ -994,7 +994,7 @@ class ExternallyConnectableMessagingWithTlsChannelIdTest :
     base::DictionaryValue jwk_value;
     net::JwkSerializer::ConvertSpkiFromDerToJwk(spki, &jwk_value);
     std::string tls_channel_id_value;
-    base::JSONWriter::Write(&jwk_value, &tls_channel_id_value);
+    base::JSONWriter::Write(jwk_value, &tls_channel_id_value);
     return tls_channel_id_value;
   }