ash: Improve low-battery notification thresholds.

ash/system/chromeos/power/tray_power.h

Index: ash/system/chromeos/power/tray_power.h
diff --git a/ash/system/chromeos/power/tray_power.h b/ash/system/chromeos/power/tray_power.h
index 2a66cd5e4aba35d5c41065a7b0412cf074dfa532..9fb65b716918a092b20bf6d372d939f32b2b6114 100644
--- a/ash/system/chromeos/power/tray_power.h
+++ b/ash/system/chromeos/power/tray_power.h
@@ -41,6 +41,16 @@ class ASH_EXPORT TrayPower : public SystemTrayItem,
     NOTIFICATION_CRITICAL,
   };
 
+  // Time-based notification thresholds when on battery power.
+  static const int kCriticalMinutes;
+  static const int kLowPowerMinutes;
+  static const int kNoWarningMinutes;
+
+  // Percentage-based notification thresholds when using a low-power charger.
+  static const int kCriticalPercentage;
+  static const int kLowPowerPercentage;
+  static const int kNoWarningPercentage;
+
   TrayPower(SystemTray* system_tray,
             message_center::MessageCenter* message_center);
   virtual ~TrayPower();