[Android] Add a "quiet" flag so KillAll doesn't complain if no processes killed

build/android/pylib/gtest/local_device_gtest_run.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.
 
 
 import logging
 import os
 
 from pylib import constants
 from pylib import ports
@@ skipping 94 matching lines @@
     # for long shell commands lands.
     with device_temp_file.DeviceTempFile(device.adb) as script_file:
       script_contents = ' '.join(cmd)
       logging.info('script contents: %r' % script_contents)
       device.WriteFile(script_file.name, script_contents)
       output = device.RunShellCommand(['sh', script_file.name], cwd=cwd,
                                       env=env, **kwargs)
     return output
 
   def Clear(self, device):
-    try:
-      device.KillAll(self._exe_file_name, blocking=True, timeout=30, retries=0)
-    except device_errors.CommandFailedError:
-      # Raised if there is no process with the given name, which in this case
-      # is all we care about.
-      pass
+    device.KillAll(self._exe_file_name, blocking=True, timeout=30, quiet=True)
 
 
 class LocalDeviceGtestRun(local_device_test_run.LocalDeviceTestRun):
 
   def __init__(self, env, test_instance):
     assert isinstance(env, local_device_environment.LocalDeviceEnvironment)
     assert isinstance(test_instance, gtest_test_instance.GtestTestInstance)
     super(LocalDeviceGtestRun, self).__init__(env, test_instance)
 
     if self._test_instance.apk:
@@ skipping 70 matching lines @@
     return results
 
   #override
   def TearDown(self):
     def individual_device_tear_down(dev):
       for s in self._servers[str(dev)]:
         s.TearDown()
 
     self._env.parallel_devices.pMap(individual_device_tear_down)