blink_rename_merge_helper: roll clang tool binaries in COMPONENTS

tools/blink_rename_merge_helper/run.py

 #!/usr/bin/env python
 # Copyright 2017 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.
 """Tool to help developers rebase branches across the Blink rename."""
 
+import argparse
 import json
 import os
 import subprocess
 import shutil
 import sys
 import tempfile
 
 
 class _DepotToolsNotFoundException(Exception):
   pass
@@ skipping 54 matching lines @@
         % (path, path2))
 
   return DepotToolsWrapper(path)
 
 
 class Bootstrapper(object):
   """Helper class for bootstrapping startup of the rebase helper.
 
   Performs update checks and stages any required binaries."""
 
-  def __init__(self, depot_tools):
+  def __init__(self, depot_tools, components_path_override):
     """Bootstrapper constructor.
 
     Args:
       depot_tools: a wrapper for invoking depot_tools.
+      components_path_override: If set, used as the path for the COMPONENTS file
+          rather than using the copy in the Google Storage bucket.
     """
     self.__depot_tools = depot_tools
+    self.__components_path_override = components_path_override
     self.__tmpdir = None
 
   def __enter__(self):
     self.__tmpdir = tempfile.mkdtemp()
     return self
 
   def __exit__(self, exc_type, exc_value, traceback):
     shutil.rmtree(self.__tmpdir, ignore_errors=True)
 
   def update(self):
     """Performs an update check for various components."""
     components = self._get_latest_components()
     for name, sha1_hash in components.iteritems():
       args = [
           '--no_auth', '--no_resume', '-b', 'chromium-blink-rename',
           '--extract', sha1_hash
       ]
       if '-' in name:
         name, platform = name.split('-', 1)
         args.append('-p')
         args.append(platform)
       args.append('-o')
       args.append(os.path.join('staging', '%s.tar.gz' % name))
       self.__depot_tools.call_download_from_google_storage(*args)
 
   def _get_latest_components(self):
     """Fetches info about the latest components from google storage.
 
     The return value should be a dict of component names to SHA1 hashes."""
-    hashes_path = os.path.join(self.__tmpdir, 'COMPONENTS')
-    self.__depot_tools.call_gsutil(
-        'cp', 'gs://chromium-blink-rename/COMPONENTS', hashes_path)
-    with open(hashes_path) as f:
+    components_path = self.__components_path_override
+    if not components_path:
+      components_path = os.path.join(self.__tmpdir, 'COMPONENTS')
+      self.__depot_tools.call_gsutil(
+          'cp', 'gs://chromium-blink-rename/COMPONENTS', components_path)
+    with open(components_path) as f:
       return json.loads(f.read())
 
 
 def main():
+  # Intentionally suppress help. These are internal testing flags.
+  parser = argparse.ArgumentParser(add_help=False)
+  parser.add_argument('--components-file')
+  args, remaining_argv = parser.parse_known_args()
+
   script_dir = os.path.dirname(os.path.realpath(__file__))
   os.chdir(script_dir)
 
   try:
     depot_tools = _find_depot_tools()
   except _DepotToolsNotFoundException as e:
     print e.message
     return 1
 
   print 'Checking for updates...'
-  with Bootstrapper(depot_tools) as bootstrapper:
+  with Bootstrapper(depot_tools, args.components_file) as bootstrapper:
     bootstrapper.update()
 
   # Import stage 2 and launch it.
   tool_pylib = os.path.abspath(os.path.join(script_dir, 'staging/pylib'))
   sys.path.insert(0, tool_pylib)
   from blink_rename_merge_helper import driver
+  # Note: for compatibility with older versions of run.py, set sys.argv to the
+  # unconsumed args.
+  sys.argv = sys.argv[:1] + remaining_argv
   driver.run()
 
 
 if __name__ == '__main__':
   sys.exit(main())