Update protobuf to r428, part 1.

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

Index: third_party/protobuf/python/google/protobuf/message.py
===================================================================
--- third_party/protobuf/python/google/protobuf/message.py	(revision 216642)
+++ third_party/protobuf/python/google/protobuf/message.py	(working copy)
@@ -73,6 +73,7 @@
     return clone
 
   def __eq__(self, other_msg):
+    """Recursively compares two messages by value and structure."""
     raise NotImplementedError
 
   def __ne__(self, other_msg):
@@ -83,9 +84,11 @@
     raise TypeError('unhashable object')
 
   def __str__(self):
+    """Outputs a human-readable representation of the message."""
     raise NotImplementedError
 
   def __unicode__(self):
+    """Outputs a human-readable representation of the message."""
     raise NotImplementedError
 
   def MergeFrom(self, other_msg):
@@ -266,3 +269,12 @@
     via a previous _SetListener() call.
     """
     raise NotImplementedError
+
+  def __getstate__(self):
+    """Support the pickle protocol."""
+    return dict(serialized=self.SerializePartialToString())
+
+  def __setstate__(self, state):
+    """Support the pickle protocol."""
+    self.__init__()
+    self.ParseFromString(state['serialized'])