arc: Revamp the ArcBridgeService interface

components/arc/power/arc_power_bridge.h

Index: components/arc/power/arc_power_bridge.h
diff --git a/components/arc/power/arc_power_bridge.h b/components/arc/power/arc_power_bridge.h
index d82aad664293a37e410527605ab3df16b3f2db4a..c82c380ce05aab53e3cf6463f1122bb929ba8618 100644
--- a/components/arc/power/arc_power_bridge.h
+++ b/components/arc/power/arc_power_bridge.h
@@ -10,6 +10,7 @@
 #include "base/macros.h"
 #include "components/arc/arc_bridge_service.h"
 #include "components/arc/arc_service.h"
+#include "components/arc/instance_holder.h"
 #include "mojo/public/cpp/bindings/binding.h"
 #include "ui/display/chromeos/display_configurator.h"
 
@@ -18,16 +19,16 @@ namespace arc {
 // ARC Power Client sets power management policy based on requests from
 // ARC instances.
 class ArcPowerBridge : public ArcService,
-                       public ArcBridgeService::Observer,
+                       public InstanceHolder<mojom::PowerInstance>::Observer,
                        public ui::DisplayConfigurator::Observer,
                        public mojom::PowerHost {
  public:
   explicit ArcPowerBridge(ArcBridgeService* bridge_service);
   ~ArcPowerBridge() override;
 
-  // ArcBridgeService::Observer overrides.
-  void OnPowerInstanceReady() override;
-  void OnPowerInstanceClosed() override;
+  // InstanceHolder<mojom::PowerInstance>::Observer overrides.
+  void OnInstanceReady() override;
+  void OnInstanceClosed() override;
 
   // DisplayConfigurator::Observer overrides.
   void OnPowerStateChanged(chromeos::DisplayPowerState power_state) override;