Merge pull request #4811 from htuch/invalid-name-json

json: include field name in InvalidName status messages.
diff --git a/src/google/protobuf/util/json_util.cc b/src/google/protobuf/util/json_util.cc
index f81a7a3..9ad073d 100644
--- a/src/google/protobuf/util/json_util.cc
+++ b/src/google/protobuf/util/json_util.cc
@@ -127,7 +127,8 @@
   virtual void InvalidName(const converter::LocationTrackerInterface& loc,
                            StringPiece unknown_name, StringPiece message) {
     status_ = util::Status(util::error::INVALID_ARGUMENT,
-                             loc.ToString() + ": " + string(message));
+                           loc.ToString() + ": invalid name " +
+                               string(unknown_name) + ": " + string(message));
   }
 
   virtual void InvalidValue(const converter::LocationTrackerInterface& loc,