Add new script to stop a kvm using vm library and use in harness.

bin/cros_au_test_harness.py

Index: bin/cros_au_test_harness.py
diff --git a/bin/cros_au_test_harness.py b/bin/cros_au_test_harness.py
index 6e537036aee10916490d24ef72bb76fe3fbd8c73..5d5b221760c0dab765dd10645ca088f2daf24681 100755
--- a/bin/cros_au_test_harness.py
+++ b/bin/cros_au_test_harness.py
@@ -446,12 +446,10 @@ class VirtualAUTest(unittest.TestCase, AUTest):
     if os.path.exists(pid_file):
       Warning('Existing %s found.  Deleting and killing process' %
               pid_file)
-      pid = RunCommand(['sudo', 'cat', pid_file], redirect_stdout=True,
-                       enter_chroot=False)
-      if pid:
-        RunCommand(['sudo', 'kill', pid.strip()], error_ok=True,
-                   enter_chroot=False)
-        RunCommand(['sudo', 'rm', pid_file], enter_chroot=False)
+      RunCommand(['./cros_stop_vm', '--kvm_pid=%s' % pid_file],
+                 cwd=self.crosutilsbin)
+
+    assert not os.path.exists(pid_file)
 
   def setUp(self):
     """Unit test overriden method.  Is called before every test."""