third_party/protobuf: Update to HEAD (83d681ee2c)

third_party/protobuf/src/google/protobuf/unittest.proto

Index: third_party/protobuf/src/google/protobuf/unittest.proto
diff --git a/third_party/protobuf/src/google/protobuf/unittest.proto b/third_party/protobuf/src/google/protobuf/unittest.proto
index da56ae0a2449c6396b4963995b73fbcbcdb006d9..cc2f4b34a003ff156081d44bccbd1ae624d8df66 100644
--- a/third_party/protobuf/src/google/protobuf/unittest.proto
+++ b/third_party/protobuf/src/google/protobuf/unittest.proto
@@ -195,6 +195,7 @@ message TestDeprecatedFields {
 // that.
 message ForeignMessage {
   optional int32 c = 1;
+  optional int32 d = 2;
 }
 
 enum ForeignEnum {
@@ -877,3 +878,11 @@ service TestService {
 message BarRequest  {}
 message BarResponse {}
 
+message TestJsonName {
+  optional int32 field_name1 = 1;
+  optional int32 fieldName2 = 2;
+  optional int32 FieldName3 = 3;
+  optional int32 _field_name4 = 4;
+  optional int32 FIELD_NAME5 = 5;
+  optional int32 field_name6 = 6 [json_name = "@type"];
+}