third_party/protobuf: Update to HEAD (83d681ee2c)

third_party/protobuf/src/google/protobuf/unittest_custom_options.proto

Index: third_party/protobuf/src/google/protobuf/unittest_custom_options.proto
diff --git a/third_party/protobuf/src/google/protobuf/unittest_custom_options.proto b/third_party/protobuf/src/google/protobuf/unittest_custom_options.proto
index 4cc0e362c56c74374b4183965ddd69834583f0cc..218447e9aa5d70c2b4fbb56dce860133eb7c3672 100644
--- a/third_party/protobuf/src/google/protobuf/unittest_custom_options.proto
+++ b/third_party/protobuf/src/google/protobuf/unittest_custom_options.proto
@@ -69,6 +69,10 @@ extend google.protobuf.FieldOptions {
   optional int32 field_opt2 = 7753913 [default=42];
 }
 
+extend google.protobuf.OneofOptions {
+  optional int32 oneof_opt1 = 7740111;
+}
+
 extend google.protobuf.EnumOptions {
   optional sfixed32 enum_opt1 = 7753576;
 }
@@ -100,6 +104,11 @@ message TestMessageWithCustomOptions {
   optional string field1 = 1 [ctype=CORD,
                               (field_opt1)=8765432109];
 
+  oneof AnOneof {
+    option (oneof_opt1) = -99;
+    int32 oneof_field = 2;
+  }
+
   enum AnEnum {
     option (enum_opt1) = -789;