chromeos: Add separate screen dim/off delays for lock screen

chrome/common/pref_names.cc

Index: chrome/common/pref_names.cc
diff --git a/chrome/common/pref_names.cc b/chrome/common/pref_names.cc
index f38bb726e52db7b01b3a77961d780c8072546fe2..e2bd2926c54da0bde5388299f89f1fa35ffa0dfe 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -715,6 +715,11 @@ const char kPowerBatteryIdleWarningDelayMs[] =
 const char kPowerBatteryIdleDelayMs[] =
     "power.battery_idle_delay_ms";
 
+// Inactivity delays used to dim the screen or turn it off while the screen is
+// locked.
+const char kPowerLockScreenDimDelayMs[] = "power.lock_screen_dim_delay_ms";
+const char kPowerLockScreenOffDelayMs[] = "power.lock_screen_off_delay_ms";
+
 // Action that should be performed when the idle delay is reached while the
 // system is on AC power or battery power.
 // Values are from the chromeos::PowerPolicyController::Action enum.