revive power_Backlight test

client/site_tests/power_Backlight/power_Backlight.py

 # 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 logging, os, time, utils
 from autotest_lib.client.bin import test
 from autotest_lib.client.common_lib import error, site_power_status, site_ui, \
                                            utils
 
 class power_Backlight(test.test):
     version = 1
 
 
     def run_once(self, delay=60, seconds=10, tries=20):
-        # disable screen locker and powerd
-        os.system('stop screen-locker')
+        # disable powerd
         os.system('stop powerd')
 
         # disable screen blanking. Stopping screen-locker isn't
         # synchronous :(. Add a sleep for now, till powerd comes around
         # and fixes all this for us.
         # TODO(davidjames): Power manager should support this feature directly
         time.sleep(5)
-        site_ui.xsystem('xset s off')
-        site_ui.xsystem('xset dpms 0 0 0')
-        site_ui.xsystem('xset -dpms')
+        site_ui.xsystem('LD_LIBRARY_PATH=/usr/local/lib ' + 'xset s off')
+        site_ui.xsystem('LD_LIBRARY_PATH=/usr/local/lib ' + 'xset dpms 0 0 0')
+        site_ui.xsystem('LD_LIBRARY_PATH=/usr/local/lib ' + 'xset -dpms')

[Sameer Nanda, 2010/08/25 20:48:48]

The three xset calls can be taken out now since powerd has now taken over this
functionality. Just stopping powerd is sufficient now.

In fact, the entire block above including the 5 sec sleep and the comments above
it can now be nuked.

 
         status = site_power_status.get_status()
         if status.linepower[0].online:
             raise error.TestFail('Machine must be unplugged')
 
         cmd = 'backlight-tool --get_max_brightness'
         max_brightness = int(utils.system_output(cmd).rstrip())
         if max_brightness < 4:
             raise error.TestFail('Must have at least 5 backlight levels')
         keyvals = {}
@@ skipping 15 matching lines @@
         self.write_perf_keyval(keyvals)
         for i in range(1, len(levels)):
             if rates[i] <= rates[i-1]:
                 raise error.TestFail('Turning up the backlight ' \
                                      'should increase energy consumption')
 
 
     def cleanup(self):
         # Re-enable screen locker and powerd. This also re-enables dpms.
         os.system('start powerd')
-        os.system('start screen-locker')