Don't pass "" to cros_run_vm_test if vm_graphics_flag isn't set.

bin/cros_au_test_harness.py

 #!/usr/bin/python
 
 # Copyright (c) 2010 The Chromium OS 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 optparse
 import os
 import sys
 import unittest
@@ skipping 256 matching lines @@
                 '--persist',
                 '--kvm_pid=%s' % _KVM_PID_FILE,
                 stateful_change_flag,
                 '--src_image=%s' % self.source_image,
                ], enter_chroot=False)
 
   def VerifyImage(self, percent_required_to_pass):
     """Runs vm smoke suite to verify image."""
     # image_to_live already verifies lsb-release matching.  This is just
     # for additional steps.
-    output = RunCommand(['%s/cros_run_vm_test' % self.crosutilsbin,
-                         '--image_path=%s' % self.vm_image_path,
-                         '--snapshot',
-                         '--persist',
-                         vm_graphics_flag,
-                         '--kvm_pid=%s' % _KVM_PID_FILE,
-                         '--test_case=%s' % _VERIFY_SUITE,
-                         ], error_ok=True, enter_chroot=False,
-                            redirect_stdout=True)
+
+    commandWithArgs = ['%s/cros_run_vm_test' % self.crosutilsbin,
+                       '--image_path=%s' % self.vm_image_path,
+                       '--snapshot',
+                       '--persist',
+                       '--kvm_pid=%s' % _KVM_PID_FILE,
+                       _VERIFY_SUITE,
+                       ]
+
+    if vm_graphics_flag:
+      commandWithArgs.append(vm_graphics_flag)
+
+    output = RunCommand(commandWithArgs, error_ok=True, enter_chroot=False,
+                        redirect_stdout=True)
     return self.CommonVerifyImage(self, output, percent_required_to_pass)
 
 
 if __name__ == '__main__':
   parser = optparse.OptionParser()
   parser.add_option('-b', '--base_image',
                     help='path to the base image.')
   parser.add_option('-t', '--target_image',
                     help='path to the target image.')
   parser.add_option('-r', '--board',
@@ skipping 47 matching lines @@
     else:
       remote = options.remote
 
     suite = unittest.TestLoader().loadTestsFromTestCase(RealAUTest)
     test_result = unittest.TextTestRunner(verbosity=2).run(suite)
   else:
     parser.error('Could not parse harness type %s.' % options.type)
 
   if not test_result.wasSuccessful():
     Die('Test harness was not successful')