[Android] Refactor the buildbot scripts to prepare for downstream usage.

build/android/buildbot/bb_host_steps.py

 #!/usr/bin/env python
 # Copyright 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.
 
 import os
 import sys
 
 import bb_utils
 
@@ skipping 86 matching lines @@
 
 def BisectPerfRegression(_):
   buildbot_report.PrintNamedStep('Bisect Perf Regression')
   RunCmd([SrcPath('tools', 'prepare-bisect-perf-regression.py'),
           '-w', os.path.join(constants.DIR_SOURCE_ROOT, os.pardir)])
   RunCmd([SrcPath('tools', 'run-bisect-perf-regression.py'),
           '-w', os.path.join(constants.DIR_SOURCE_ROOT, os.pardir),
           '-p', bb_utils.GOMA_DIR])
 
 
-def GetHostSteps():
+def GetHostStepCmds():
   return [
       ('compile', Compile),
       ('extract_build', ExtractBuild),
       ('check_webview_licenses', CheckWebViewLicenses),
       ('bisect_perf_regression', BisectPerfRegression),
       ('findbugs', FindBugs),
       ('zip_build', ZipBuild)
   ]
 
 
-def main(argv):
+def GetHostStepsOptParser():
   parser = bb_utils.GetParser()
   parser.add_option('--steps', help='Comma separated list of host tests.')
   parser.add_option('--build-targets', default='All',
                     help='Comma separated list of build targets.')
   parser.add_option('--experimental', action='store_true',
                     help='Indicate whether to compile experimental targets.')
 
+  return parser
+
+
+def main(argv):
+  parser = GetHostStepsOptParser()
   options, args = parser.parse_args(argv[1:])
   if args:
     return sys.exit('Unused args %s' % args)
 
   setattr(options, 'target', options.factory_properties.get('target', 'Debug'))
 
-  bb_utils.RunSteps(GetHostSteps(), options)
+  if options.steps:
+    bb_utils.RunSteps(options.steps.split(','), GetHostStepCmds(), options)
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))