Bump vendoring, move to proto3 release.

bootstrap/update_vendoring.py

 #!/usr/bin/env python
 # Copyright 2016 The LUCI Authors. All rights reserved.
 # Use of this source code is governed under the Apache License, Version 2.0
 # that can be found in the LICENSE file.
 
 """Regenerates vendored components and derivative files from external sources.
 
 This is a utililty script that is intended to be run on a Linux-based system.
 Other operating systems may work, but are not supported.
 
@@ skipping 247 matching lines @@
     _VendoredGitRepo(
         'recipe_engine/third_party/client-py/libs',
         repo='https://github.com/luci/client-py',
         ref='origin/master',
         subpath='libs'),
 
     # All actions that rely on "protoc" must happen after this one.
     _VendoredPythonProtobuf(
         'recipe_engine/third_party/google',
         repo='https://github.com/google/protobuf',
-        ref='3.0.0-beta-3'),
+        ref='v3.0.0'),
 
     _VendoredLuciGoProto(
         'recipe_engine/third_party',
         relsrc='common/proto/milo',
         ref='origin/master'),
 
     _RegenerateLocalProtobufs(),
 )
 
 
@@ skipping 11 matching lines @@
       vdir = os.path.join(td, 'vendor_%d' % (i,))
       os.makedirs(vdir)
 
       # Execute the vendor script.
       act.run(c, vdir)
 
 
 if __name__ == '__main__':
   logging.basicConfig(level=logging.DEBUG)
   sys.exit(main(sys.argv[1:]))