Remove old Authentication code that we don't use or need.

remoting/proto/chromotocol.gyp

 # Copyright (c) 2010 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [
     {
       'target_name': 'chromotocol_proto_lib',
       'type': 'static_library',
       'sources': [
-        'auth.proto',
         'control.proto',
         'event.proto',
         'internal.proto',
         'video.proto',
       ],
       'variables': {
         'proto_out_dir': 'remoting/proto',
       },
       'includes': ['../../build/protoc.gypi'],
     },
   ],
 }