[Android] Switch to DeviceUtils version of RunShellCommand.

build/android/pylib/flag_changer.py

Index: build/android/pylib/flag_changer.py
diff --git a/build/android/pylib/flag_changer.py b/build/android/pylib/flag_changer.py
index c1e8cb8f34602940f377df008b039e3886c5dc4f..9ccdc1eb7ea1befea1c358aacdacc8ff8fb45c34 100644
--- a/build/android/pylib/flag_changer.py
+++ b/build/android/pylib/flag_changer.py
@@ -114,11 +114,7 @@ class FlagChanger(object):
       assert len(file_contents) == 1 and file_contents[0] == cmd_line, (
           'Failed to set the command line file at %s' % self._cmdline_file)
     else:
-      if use_root:
-        self._device.old_interface.RunShellCommandWithSU(
-            'rm ' + self._cmdline_file)
-      else:
-        self._device.old_interface.RunShellCommand('rm ' + self._cmdline_file)
+      self._device.RunShellCommand('rm ' + self._cmdline_file, root=use_root)
       assert (
           not self._device.old_interface.FileExistsOnDevice(
               self._cmdline_file)), (