Update //third_party/protobuf to version 3.

third_party/protobuf/python/google/protobuf/internal/descriptor_pool_test2.proto

Index: third_party/protobuf/python/google/protobuf/internal/descriptor_pool_test2.proto
diff --git a/third_party/protobuf/python/google/protobuf/internal/factory_test1.proto b/third_party/protobuf/python/google/protobuf/internal/descriptor_pool_test2.proto
similarity index 65%
copy from third_party/protobuf/python/google/protobuf/internal/factory_test1.proto
copy to third_party/protobuf/python/google/protobuf/internal/descriptor_pool_test2.proto
index 9f55e037f6e69ff8e76a3f260eff006af1bcce65..e3fa660ce13bae3839b73db07a8f267a4498fa62 100644
--- a/third_party/protobuf/python/google/protobuf/internal/factory_test1.proto
+++ b/third_party/protobuf/python/google/protobuf/internal/descriptor_pool_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
@@ -28,28 +28,45 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Author: matthewtoia@google.com (Matt Toia)
-
+syntax = "proto2";
 
 package google.protobuf.python.internal;
 
+import "google/protobuf/internal/descriptor_pool_test1.proto";
 
-enum Factory1Enum {
-  FACTORY_1_VALUE_0 = 0;
-  FACTORY_1_VALUE_1 = 1;
-}
 
-message Factory1Message {
-  optional Factory1Enum factory_1_enum = 1;
-  enum NestedFactory1Enum {
-    NESTED_FACTORY_1_VALUE_0 = 0;
-    NESTED_FACTORY_1_VALUE_1 = 1;
+message DescriptorPoolTest3 {
+
+  extend DescriptorPoolTest1 {
+    optional DescriptorPoolTest3 descriptor_pool_test = 1001;
+  }
+
+  enum NestedEnum {
+    NU = 13;
+    XI = 14;
   }
-  optional NestedFactory1Enum nested_factory_1_enum = 2;
-  message NestedFactory1Message {
-    optional string value = 1;
+
+  optional NestedEnum nested_enum = 1 [default = XI];
+
+  message NestedMessage {
+    enum NestedEnum {
+      OMICRON = 15;
+      PI = 16;
+    }
+    optional NestedEnum nested_enum = 1 [default = PI];
+    optional string nested_field = 2 [default = "nu"];
+    optional DeepNestedMessage deep_nested_message = 3;
+
+    message DeepNestedMessage {
+      enum NestedEnum {
+        RHO = 17;
+        SIGMA = 18;
+      }
+      optional NestedEnum nested_enum = 1 [default = RHO];
+      optional string nested_field = 2 [default = "sigma"];
+    }
   }
-  optional NestedFactory1Message nested_factory_1_message = 3;
-  optional int32 scalar_value = 4;
-  repeated string list_value = 5;
+
+  optional NestedMessage nested_message = 2;
 }
+