revive power_Backlight test

client/site_tests/power_Backlight/power_Backlight.py

Index: client/site_tests/power_Backlight/power_Backlight.py
diff --git a/client/site_tests/power_Backlight/power_Backlight.py b/client/site_tests/power_Backlight/power_Backlight.py
index 8157a12f36e22f65ea235a04e0af225c94094be2..8845759a9c4e093109f1ec0c15cfe0b9edab615a 100644
--- a/client/site_tests/power_Backlight/power_Backlight.py
+++ b/client/site_tests/power_Backlight/power_Backlight.py
@@ -12,8 +12,7 @@ class power_Backlight(test.test):
 
 
     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
@@ -21,9 +20,9 @@ class power_Backlight(test.test):
         # 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:
@@ -59,5 +58,4 @@ class power_Backlight(test.test):
     def cleanup(self):
         # Re-enable screen locker and powerd. This also re-enables dpms.
         os.system('start powerd')
-        os.system('start screen-locker')