Update third_party/protobuf to protobuf-v3.0.0-beta-3

third_party/protobuf/examples/add_person.py

 #! /usr/bin/env python
 
 # See README.txt for information and build instructions.
 
 import addressbook_pb2
 import sys
 
 # This function fills in a Person message based on user input.
 def PromptForAddress(person):
   person.id = int(raw_input("Enter person ID number: "))
@@ skipping 25 matching lines @@
 #   adds one person based on user input, then writes it back out to the same
 #   file.
 if len(sys.argv) != 2:
   print "Usage:", sys.argv[0], "ADDRESS_BOOK_FILE"
   sys.exit(-1)
 
 address_book = addressbook_pb2.AddressBook()
 
 # Read the existing address book.
 try:
-  f = open(sys.argv[1], "rb")
-  address_book.ParseFromString(f.read())
-  f.close()
+  with open(sys.argv[1], "rb") as f:
+    address_book.ParseFromString(f.read())
 except IOError:
   print sys.argv[1] + ": File not found.  Creating a new file."
 
 # Add an address.
 PromptForAddress(address_book.people.add())
 
 # Write the new address book back to disk.
-f = open(sys.argv[1], "wb")
-f.write(address_book.SerializeToString())
-f.close()
+with open(sys.argv[1], "wb") as f:
+  f.write(address_book.SerializeToString())