Kill simctl before starting iOS simulator tests

ios/build/bots/scripts/test_runner.py

 # Copyright 2016 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.
 
 """Test runners for iOS."""
 
 import argparse
 import collections
 import errno
 import os
@@ skipping 379 matching lines @@
   def kill_simulators():
     """Kills all running simulators."""
     try:
       subprocess.check_call([
           'pkill',
           '-9',
           '-x',
           # The simulator's name varies by Xcode version.
           'iPhone Simulator', # Xcode 5
           'iOS Simulator', # Xcode 6
-          'Simulator', # Xcode 7
+          'Simulator', # Xcode 7+
+          'simctl', # https://crbug.com/637429
       ])
     except subprocess.CalledProcessError as e:
       if e.returncode != 1:
         # Ignore a 1 exit code (which means there were no simulators to kill).
         raise
 
   def wipe_simulator(self):
     """Wipes the simulator."""
     subprocess.check_call([
         self.iossim_path,
@@ skipping 255 matching lines @@
       A dict of environment variables.
     """
     env = super(DeviceTestRunner, self).get_launch_env()
     if self.xctest_path:
       # e.g. ios_web_shell_test_host
       env['APP_TARGET_NAME'] = (
         os.path.splitext(os.path.basename(self.app_path))[0])
       # e.g. ios_web_shell_test
       env['TEST_TARGET_NAME'] = env['APP_TARGET_NAME'].rsplit('_', 1)[0]
     return env