Fix force stop using wrong "ps" cmd.

devil/devil/android/device_utils.py

Index: devil/devil/android/device_utils.py
diff --git a/devil/devil/android/device_utils.py b/devil/devil/android/device_utils.py
index 50f362c3839974e7d296ff08c6cc7669b63b3a85..de7cc5cc87e06f4d1014e3f06323394388cbf380 100644
--- a/devil/devil/android/device_utils.py
+++ b/devil/devil/android/device_utils.py
@@ -1181,8 +1181,9 @@ class DeviceUtils(object):
       CommandTimeoutError on timeout.
       DeviceUnreachableError on missing device.
     """
-    cmd = 'p=%s;if [[ "$(ps)" = *$p* ]]; then am force-stop $p; fi'
-    self.RunShellCommand(cmd % package, shell=True, check_return=True)
+    cmd = ('p=%s;if [[ "$(%s)" = *$p* ]]; then am force-stop $p; fi' %

[jbudorick, 2017/04/11 23:47:24]

I'm wondering if maintaining the hotrolled script here is worth it vs switching
to

  if self.GetPids(process_name=package):
    self.RunShellCommand(['am', 'force-stop', package], check_return=True)

[perezju, 2017/04/12 09:13:20]

+1

+        (package, self._GetPsCommand()))
+    self.RunShellCommand(cmd, shell=True, check_return=True)
 
   @decorators.WithTimeoutAndRetriesFromInstance()
   def ClearApplicationState(
@@ -2153,11 +2154,7 @@ class DeviceUtils(object):
     """
     procs_pids = collections.defaultdict(list)
     try:
-      ps_cmd = 'ps'
-      # ps behavior was changed in Android above N, http://crbug.com/686716
-      if (self.build_version_sdk >= version_codes.NOUGAT_MR1
-          and self.build_id[0] > 'N'):
-        ps_cmd = 'ps -e'
+      ps_cmd = self._GetPsCommand()
       if process_name:
         ps_output = self._RunPipedShellCommand(
             '%s | grep -F %s' % (ps_cmd, cmd_helper.SingleQuote(process_name)))
@@ -2638,3 +2635,16 @@ class DeviceUtils(object):
       return
     self.SendKeyEvent(keyevent.KEYCODE_POWER)
     timeout_retry.WaitFor(screen_test, wait_period=1)
+
+  def _GetPsCommand(self):
+    """Returns command to get list of processes.
+
+    Command to get list of processes is different for differnet Android
+    versions.
+    """
+    ps_cmd = 'ps'
+    # ps behavior was changed in Android above N, http://crbug.com/686716
+    if (self.build_version_sdk >= version_codes.NOUGAT_MR1
+        and self.build_id[0] > 'N'):
+      ps_cmd = 'ps -e'
+    return ps_cmd