Refactor fetch_benchmark_deps.py script to allow fetching all benchmark deps

tools/perf/fetch_benchmark_deps_unittest.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 os
-import sys
 import unittest
 import StringIO
 
 import mock  # pylint: disable=import-error
 
 from core import path_util
 import fetch_benchmark_deps
 
 
 def NormPaths(paths):
   return sorted([os.path.normcase(p) for p in paths.splitlines()])
 
 
 class FetchBenchmarkDepsUnittest(unittest.TestCase):
   """The test guards fetch_benchmark_deps.
 
   It assumes the following telemetry APIs always success:
   telemetry.wpr.archive_info.WprArchiveInfo.DownloadArchivesIfNeeded
   py_utils.cloud_storage.GetFilesInDirectoryIfChanged
   """
 
-  def setUp(self):
-    """Override sys.argv as if it is called from command line."""
-    self._argv = sys.argv
-    sys.argv = ['./fetch_benchmark_deps', '']
-
   def _RunFetchBenchmarkDepsTest(self, benchmark_name,
                                  expected_fetched_file_paths=None):
     """Simulates './fetch_benchmark_deps [benchmark_name]'
 
     It checks if the paths returned are expected and have corresponding sha1
     checksums. The expected result can be omitted if the dependencies of
     specified benchmarks are subject to changes.
 
     Args:
       benchmark_name: benchmark name
       expected_fetched_file_paths: the expected result.
     """
-    sys.argv[1] = benchmark_name
+    args = [benchmark_name]
     output = StringIO.StringIO()
     with mock.patch('telemetry.wpr.archive_info.WprArchiveInfo'
                     '.DownloadArchivesIfNeeded') as mock_download:
       with mock.patch('py_utils.cloud_storage'
                       '.GetFilesInDirectoryIfChanged') as mock_get:
         mock_download.return_value = True
         mock_get.GetFilesInDirectoryIfChanged.return_value = True
-        fetch_benchmark_deps.main(output)
+        fetch_benchmark_deps.main(args, output)
     for f in output.getvalue().splitlines():
       fullpath = os.path.join(path_util.GetChromiumSrcDir(), f)
       sha1path = fullpath + '.sha1'
       self.assertTrue(os.path.isfile(sha1path))
     if expected_fetched_file_paths:
       self.assertEquals(expected_fetched_file_paths,
                         NormPaths(output.getvalue()))
 
   def testFetchWPRs(self):
     self._RunFetchBenchmarkDepsTest('smoothness.top_25_smooth')
 
   def testFetchServingDirs(self):
     self._RunFetchBenchmarkDepsTest('media.tough_video_cases')
 
   def testFetchOctane(self):
     octane_wpr_path = os.path.join(
         os.path.dirname(__file__), 'page_sets', 'data', 'octane_002.wpr')
     expected = os.path.relpath(octane_wpr_path,
                                path_util.GetChromiumSrcDir())
     self._RunFetchBenchmarkDepsTest('octane', NormPaths(expected))