Make [S,G]getBacklightsForcedOff dbus API integrated to power_manager_client

chromeos/dbus/fake_power_manager_client.h

Index: chromeos/dbus/fake_power_manager_client.h
diff --git a/chromeos/dbus/fake_power_manager_client.h b/chromeos/dbus/fake_power_manager_client.h
index fc6bbae2f83b546040ed6a7c47dfab38448f01a2..607a54e01572be8300bf42ed117c9a5659729480 100644
--- a/chromeos/dbus/fake_power_manager_client.h
+++ b/chromeos/dbus/fake_power_manager_client.h
@@ -63,6 +63,9 @@ class CHROMEOS_EXPORT FakePowerManagerClient : public PowerManagerClient {
   void SetPolicy(const power_manager::PowerManagementPolicy& policy) override;
   void SetIsProjecting(bool is_projecting) override;
   void SetPowerSource(const std::string& id) override;
+  void SetBacklightsForcedOff(bool is_off) override;
+  void GetBacklightsForcedOffState(
+      const GetBacklightsForcedOffStateCallback& callback) override;
   base::Closure GetSuspendReadinessCallback() override;
   int GetNumPendingSuspendReadinessCallbacks() override;