Fix dart apptest flake on android.

mojo/devtools/common/devtoolslib/apptest_dart.py

 # Copyright 2014 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.
 
 """Apptest runner specific to the particular Dart apptest framework in
 /mojo/dart/apptests, built on top of the general apptest runner."""
 
 import logging
 import re
 
 _logging = logging.getLogger()
 
 from devtoolslib.apptest import run_apptest
 
-SUCCESS_PATTERN = re.compile('^.+ .+: All tests passed!', re.MULTILINE)
+# The apptest framework guarantees that tearDownAll() is the last thing to be
+# called before the shell is terminated. Note that the shell may be terminated
+# before the "All tests passed!" string.
+#
+# So we pass on messages like:
+#   00:01 +3: (tearDownAll)
+# And fail on messages like:
+#   00:01 +2 -1: (tearDownAll)
+SUCCESS_PATTERN = re.compile(r'^\S+ \S+: \(tearDownAll\)', re.MULTILINE)
 
 
 def _dart_apptest_output_test(output):
   return SUCCESS_PATTERN.search(output) is not None
 
 
 # TODO(erg): Support android, launched services and fixture isolation.
 def run_dart_apptest(shell, shell_args, apptest_url, apptest_args, timeout):
   """Runs a dart apptest.
 
   Args:
     shell_args: The arguments for mojo_shell.
     apptest_url: Url of the apptest app to run.
     apptest_args: Parameters to be passed to the apptest app.
 
   Returns:
     True iff the test succeeded, False otherwise.
   """
   return run_apptest(shell, shell_args, apptest_url, apptest_args, timeout,
                      _dart_apptest_output_test)