third_party/protobuf: Update to HEAD (83d681ee2c)

third_party/protobuf/src/google/protobuf/test_util.cc

Index: third_party/protobuf/src/google/protobuf/test_util.cc
diff --git a/third_party/protobuf/src/google/protobuf/test_util.cc b/third_party/protobuf/src/google/protobuf/test_util.cc
index 07aa1d7781b55459768c96ca7fbae85fe10ffd36..658c8ee285fbd18b975d94b27ffe64b37768458f 100644
--- a/third_party/protobuf/src/google/protobuf/test_util.cc
+++ b/third_party/protobuf/src/google/protobuf/test_util.cc
@@ -3332,7 +3332,11 @@ void TestUtil::ReflectionTester::ExpectMessagesReleasedViaReflection(
         break;
       case NOT_NULL:
         EXPECT_TRUE(released != NULL);
-        EXPECT_EQ(&sub_message, released);
+        if (message->GetArena() == NULL) {
+          // released message must be same as sub_message if source message is
+          // not on arena.
+          EXPECT_EQ(&sub_message, released);
+        }
         break;
       case CAN_BE_NULL:
         break;