Update //third_party/protobuf to version 3.

third_party/protobuf/python/google/protobuf/internal/factory_test2.proto

Index: third_party/protobuf/python/google/protobuf/internal/factory_test2.proto
diff --git a/third_party/protobuf/python/google/protobuf/internal/factory_test2.proto b/third_party/protobuf/python/google/protobuf/internal/factory_test2.proto
index d3ce4d7f95c0894534d51d7e63422bb8986d8249..bb1b54ada2b1e9b23bdf0d6682c2d3e9f31775fd 100644
--- a/third_party/protobuf/python/google/protobuf/internal/factory_test2.proto
+++ b/third_party/protobuf/python/google/protobuf/internal/factory_test2.proto
@@ -1,6 +1,6 @@
 // Protocol Buffers - Google's data interchange format
 // Copyright 2008 Google Inc.  All rights reserved.
-// http://code.google.com/p/protobuf/
+// https://developers.google.com/protocol-buffers/
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
@@ -30,6 +30,7 @@
 
 // Author: matthewtoia@google.com (Matt Toia)
 
+syntax = "proto2";
 
 package google.protobuf.python.internal;
 
@@ -70,8 +71,29 @@ message Factory2Message {
   optional string string_with_default = 18 [default = "hello world"];
   optional bool bool_with_default = 19 [default = false];
   optional Factory2Enum enum_with_default = 20 [default = FACTORY_2_VALUE_1];
+  optional bytes bytes_with_default = 21 [default = "a\373\000c"];
+
+
+  extend Factory1Message {
+    optional string one_more_field = 1001;
+  }
+
+  oneof oneof_field {
+    int32 oneof_int = 22;
+    string oneof_string = 23;
+  }
 }
 
 message LoopMessage {
   optional Factory2Message loop = 1;
 }
+
+message MessageWithNestedEnumOnly {
+  enum NestedEnum {
+    NESTED_MESSAGE_ENUM_0 = 0;
+  }
+}
+
+extend Factory1Message {
+  optional string another_field = 1002;
+}