Add a new script bb_host_steps.py which handles all host side steps.

build/android/PRESUBMIT.py

 # Copyright (c) 2013 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.
 
 """Presubmit script for android buildbot.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts for
 details on the presubmit API built into gcl.
 """
 
@@ skipping 22 matching lines @@
 
   def J(*dirs):
     """Returns a path relative to presubmit directory."""
     return input_api.os_path.join(input_api.PresubmitLocalPath(), *dirs)
 
   output.extend(input_api.canned_checks.RunPylint(
       input_api,
       output_api,
       white_list=[r'PRESUBMIT\.py$', r'buildbot/.*\.py$'],
       extra_paths_list=[
-          J(), J('..', '..', 'third_party', 'android_testrunner')]))
+          J(), J('..', '..', 'third_party', 'android_testrunner'),
+          J('buildbot')]))
 
   output.extend(input_api.canned_checks.RunUnitTestsInDirectory(
       input_api, output_api, J('buildbot', 'tests')))
   output.extend(_CheckDeletionsOnlyFiles(input_api, output_api))
   return output
 
 
 def CheckChangeOnUpload(input_api, output_api):
   return CommonChecks(input_api, output_api)
 
 
 def CheckChangeOnCommit(input_api, output_api):
   return CommonChecks(input_api, output_api)