[lacros] Clean up checkout_presubmit_ash_chrome

This CL cleans up checkout_presubmit_ash_chrome DEPS hook because all
CI/CQ builders have been switched to build ash-chrome from ToT.

Bug: 1129223
Change-Id: I9de1f832ae29d3fe7eea85d67cd822b8c999c767
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2518080
Commit-Queue: Yuke Liao <liaoyuke@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@google.com>
Reviewed-by: Sven Zheng <svenzheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825579}

DEPS

@@ -159,9 +159,6 @@ vars = {
   # qemu on linux-arm64 machines.
   'checkout_fuchsia_for_arm64_host': False,
 
-  # Download prebuilt ash-chrome to test lacros build.
-  'checkout_prebuilt_ash_chrome': False,
-
   # By default, download the fuchsia sdk from the fuchsia GCS bucket.
   'fuchsia_sdk_bucket': 'fuchsia',
 
@@ -5015,16 +5012,6 @@ hooks = [
     ],
   },
 
-  {
-    'name': 'Download prebuilt ash-chrome',
-    'pattern': '.',
-    'condition': 'checkout_prebuilt_ash_chrome',
-    'action': [ 'vpython',
-                'src/build/lacros/test_runner.py',
-                'download_for_bots',
-    ],
-  },
-
   # Download and initialize "vpython" VirtualEnv environment packages.
   {
     'name': 'vpython_common',

build/lacros/test_runner.py

@@ -158,23 +158,9 @@ def _GsutilCopyWithRetry(gs_path, local_name, retry_times=3):
   if exit_code:
     raise RuntimeError('Failed to download: "%s"' % gs_path)
 
-def _DownloadAshChromeIfNecessary(version, is_download_for_bots=False):
-  """Download a given version of ash-chrome if not already exists.
 
-  Currently, a special constant version value is support: "for_bots", the reason
-  is that version number is still not pinned to chromium/src, so a constant
-  value is needed to make sure that after the builder who downloads and isolates
-  ash-chrome, the tester knows where to look for the binary to use.
-  Additionally, a is_download_for_bots boolean argument is introduced to
-  indicate whether this function is downloading for bots specifically or
-  downloading while running tests, and it is needed because when version is
-  "for_bots", the expected behavior is different in the 2 scenarios: when
-  downloading for bots to isolate, we always want to update for_bots/ to reflect
-  the latest version; however, when downloading while running tests, we want to
-  skip updating to latest because swarming testers aren't supposed to have
-  external network access.
-  TODO(crbug.com/1107010): remove the support once ash-chrome version is pinned
-  to chromium/src.
+def _DownloadAshChromeIfNecessary(version):
+  """Download a given version of ash-chrome if not already exists.
 
   Args:
     version: A string representing the version, such as "793554".
@@ -193,16 +179,14 @@ def _DownloadAshChromeIfNecessary(version, is_download_for_bots=False):
         os.path.join(ash_chrome_dir, 'chrome'))
 
   ash_chrome_dir = _GetAshChromeDirPath(version)
-  if not is_download_for_bots and IsAshChromeDirValid(ash_chrome_dir):
+  if IsAshChromeDirValid(ash_chrome_dir):
     return
 
   shutil.rmtree(ash_chrome_dir, ignore_errors=True)
   os.makedirs(ash_chrome_dir)
   with tempfile.NamedTemporaryFile() as tmp:
-    gs_version = (_GetLatestVersionOfAshChrome()
-                  if is_download_for_bots else version)
-    logging.info('Ash-chrome version: %s', gs_version)
-    gs_path = _GS_URL_BASE + '/' + gs_version + '/' + _GS_ASH_CHROME_PATH
+    logging.info('Ash-chrome version: %s', version)
+    gs_path = _GS_URL_BASE + '/' + version + '/' + _GS_ASH_CHROME_PATH
     _GsutilCopyWithRetry(gs_path, tmp.name)
 
     # https://bugs.python.org/issue15795. ZipFile doesn't preserve permissions.
@@ -441,13 +425,6 @@ def Main():
 
   subparsers = arg_parser.add_subparsers()
 
-  download_parser = subparsers.add_parser(
-      'download_for_bots',
-      help='Download prebuilt ash-chrome for bots so that tests are hermetic '
-      'during execution')
-  download_parser.set_defaults(
-      func=lambda *_: _DownloadAshChromeIfNecessary('for_bots', True))
-
   test_parser = subparsers.add_parser('test', help='Run tests')
   test_parser.set_defaults(func=_RunTest)
 

build/lacros/test_runner_test.py

@@ -25,16 +25,6 @@ class TestRunnerTest(unittest.TestCase):
   def tearDown(self):
     logging.disable(logging.NOTSET)
 
-  @mock.patch.object(test_runner, '_DownloadAshChromeIfNecessary')
-  # Tests 'download_for_bots' to download ash-chrome for bots to isolate.
-  # TODO(crbug.com/1107010): remove this test once ash-chrome version is pinned
-  # to chromium/src.
-  def test_download_for_bots(self, mock_download):
-    args = ['script_name', 'download_for_bots']
-    with mock.patch.object(sys, 'argv', args):
-      test_runner.Main()
-      mock_download.assert_called_with('for_bots', True)
-
   @parameterized.expand([
       'url_unittests',
       './url_unittests',