Update //third_party/protobuf to version 3.

third_party/protobuf/python/google/protobuf/message.py

Index: third_party/protobuf/python/google/protobuf/message.py
diff --git a/third_party/protobuf/python/google/protobuf/message.py b/third_party/protobuf/python/google/protobuf/message.py
index 6ec2f8beb1430d9e304ff61ae15d850c9fa1bf98..de2f5697e2993dc762a352316c9bc01cda87a799 100755
--- a/third_party/protobuf/python/google/protobuf/message.py
+++ b/third_party/protobuf/python/google/protobuf/message.py
@@ -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
@@ -36,7 +36,6 @@
 
 __author__ = 'robinson@google.com (Will Robinson)'
 
-
 class Error(Exception): pass
 class DecodeError(Error): pass
 class EncodeError(Error): pass
@@ -177,7 +176,11 @@ class Message(object):
     raise NotImplementedError
 
   def ParseFromString(self, serialized):
-    """Like MergeFromString(), except we clear the object first."""
+    """Parse serialized protocol buffer data into this message.
+
+    Like MergeFromString(), except we clear the object first and
+    do not return the value that MergeFromString returns.
+    """
     self.Clear()
     self.MergeFromString(serialized)
 
@@ -229,12 +232,21 @@ class Message(object):
     raise NotImplementedError
 
   def HasField(self, field_name):
-    """Checks if a certain field is set for the message. Note if the
-    field_name is not defined in the message descriptor, ValueError will be
-    raised."""
+    """Checks if a certain field is set for the message, or if any field inside
+    a oneof group is set.  Note that if the field_name is not defined in the
+    message descriptor, ValueError will be raised."""
     raise NotImplementedError
 
   def ClearField(self, field_name):
+    """Clears the contents of a given field, or the field set inside a oneof
+    group.  If the name neither refers to a defined field or oneof group,
+    ValueError is raised."""
+    raise NotImplementedError
+
+  def WhichOneof(self, oneof_group):
+    """Returns the name of the field that is set inside a oneof group, or
+    None if no field is set.  If no group with the given name exists, ValueError
+    will be raised."""
     raise NotImplementedError
 
   def HasExtension(self, extension_handle):