Add priority groups to local paths in the dependency manager.

tools/telemetry/catapult_base/dependency_manager/dependency_manager.py

 # Copyright 2015 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 logging
 import os
 import stat
 
 from catapult_base import cloud_storage
 from catapult_base import support_binaries
@@ skipping 196 matching lines @@
 
     Will not download the file.
 
     Args:
         dependency_info: A DependencyInfo instance for the dependency to be
             found and the platform it should run on.
 
     Returns: A path to a local file, or None if not found.
     """
     if dependency_info:
-      paths = dependency_info.local_paths
-      for local_path in paths:
-        if os.path.exists(local_path):
-          return local_path
+      local_paths = dependency_info.local_paths
+      found_path = None
+      for priority_group in local_paths:
+        # A list of paths in local_paths implies the same priority, so return
+        # the most recently modified one.
+        found_path_mtime = 0
+        for path in priority_group:
+          if os.path.exists(path):
+            mtime = os.stat(path).st_mtime

[eakuefner, 2015/10/09 16:29:17]

mtime = os.path.getmtime(path)

+            if mtime > found_path_mtime:
+              found_path = path
+              found_path_mtime = mtime
+        if found_path:
+          return found_path
     return None
 
   @staticmethod
   def _CloudStoragePath(dependency_info):
     """Return a path to a downloaded file for |dependency_info|.
 
     May not download the file if it has already been downloaded.
 
     Args:
         dependency_info: A DependencyInfo instance for the dependency to be
@@ skipping 27 matching lines @@
     if not os.path.exists(download_dir):
       os.makedirs(download_dir)
 
     cloud_storage.GetIfHashChanged(cs_path, download_path, cs_bucket, cs_hash)
     if not os.path.exists(download_path):
       raise exceptions.FileNotFoundError(download_path)
     #TODO(aiolos): Add support for unzipping files.
     os.chmod(download_path,
              stat.S_IRUSR | stat.S_IWUSR | stat.S_IXUSR | stat.S_IRGRP)
     return os.path.abspath(download_path)