Add policies to control power management on the Chrome OS login screen

chromeos/dbus/power_policy_controller.h

Index: chromeos/dbus/power_policy_controller.h
diff --git a/chromeos/dbus/power_policy_controller.h b/chromeos/dbus/power_policy_controller.h
index b24aa4ac022cf52b545ba21847531e1c1263bbd7..4cf68dfc312a772a3a4c5368dbf5cfbb42aa2960 100644
--- a/chromeos/dbus/power_policy_controller.h
+++ b/chromeos/dbus/power_policy_controller.h
@@ -74,6 +74,9 @@ class CHROMEOS_EXPORT PowerPolicyController
   // Updates |prefs_policy_| with |values| and sends an updated policy.
   void ApplyPrefs(const PrefValues& values);
 
+  // Resets |prefs_policy_| to its defaults and sends an updated policy.
+  void ClearPrefs();
+
   // Registers a request to temporarily prevent the screen from getting
   // dimmed or turned off or the system from suspending in response to user
   // inactivity and sends an updated policy.  |reason| is a human-readable
@@ -94,6 +97,8 @@ class CHROMEOS_EXPORT PowerPolicyController
   virtual void PowerManagerRestarted() OVERRIDE;
 
  private:
+  friend class PowerPrefsTest;
+
   typedef std::map<int, std::string> WakeLockMap;
 
   // Sends a policy based on |prefs_policy_| to the power manager.