Don't issue Stop() for spurious command line differences.

Tools/Scripts/webkitpy/layout_tests/port/chromium_android.py

 # Copyright (C) 2012 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
@@ skipping 865 matching lines @@
         if base:
             driver_input = copy.copy(driver_input)
             driver_input.args = self._port.lookup_virtual_test_args(driver_input.test_name)
             driver_input.test_name = base
         return super(ChromiumAndroidDriver, self).run_test(driver_input, stop_when_done)
 
     def start(self, pixel_tests, per_test_args):
         # We override the default start() so that we can call _android_driver_cmd_line()
         # instead of cmd_line().
         new_cmd_line = self._android_driver_cmd_line(pixel_tests, per_test_args)
-        if new_cmd_line != self._current_cmd_line:
+
+        # Since _android_driver_cmd_line() is different than cmd_line() we need to provide
+        # our own mechanism for detecting when the process should be stopped.
+        if self._current_cmd_line is None:
+            self._current_android_cmd_line = None
+        if new_cmd_line != self._current_android_cmd_line:
             self.stop()
+        self._current_android_cmd_line = new_cmd_line
+
         super(ChromiumAndroidDriver, self).start(pixel_tests, per_test_args)
 
     def _start(self, pixel_tests, per_test_args):
         self._setup_test()
 
         for retries in range(3):
             if self._start_once(pixel_tests, per_test_args):
                 return
             self._log_error('Failed to start the content_shell application. Retries=%d. Log:%s' % (retries, self._get_logcat()))
             self.stop()
@@ skipping 117 matching lines @@
         return command
 
     def _read_prompt(self, deadline):
         last_char = ''
         while True:
             current_char = self._server_process.read_stdout(deadline, 1)
             if current_char == ' ':
                 if last_char in ('#', '$'):
                     return
             last_char = current_char