arc-bridge: Introduce the ArcService class

components/arc/power/arc_power_bridge.cc

Index: components/arc/power/arc_power_bridge.cc
diff --git a/components/arc/power/arc_power_bridge.cc b/components/arc/power/arc_power_bridge.cc
index b918147ab1ed5f3a973e44762c2fe8856e00be78..8cd34041b4df808937ca8158b1b738d7d907c37b 100644
--- a/components/arc/power/arc_power_bridge.cc
+++ b/components/arc/power/arc_power_bridge.cc
@@ -13,15 +13,13 @@
 
 namespace arc {
 
-ArcPowerBridge::ArcPowerBridge(ArcBridgeService* arc_bridge_service)
-    : arc_bridge_service_(arc_bridge_service), binding_(this) {
-  arc_bridge_service->AddObserver(this);
-  if (arc_bridge_service->power_instance())
-    OnPowerInstanceReady();
+ArcPowerBridge::ArcPowerBridge(ArcBridgeService* bridge_service)
+    : ArcService(bridge_service), binding_(this) {
+  arc_bridge_service()->AddObserver(this);
 }
 
 ArcPowerBridge::~ArcPowerBridge() {
-  arc_bridge_service_->RemoveObserver(this);
+  arc_bridge_service()->RemoveObserver(this);
   ReleaseAllDisplayWakeLocks();
 }
 
@@ -31,7 +29,7 @@ void ArcPowerBridge::OnStateChanged(ArcBridgeService::State state) {
 }
 
 void ArcPowerBridge::OnPowerInstanceReady() {
-  PowerInstance* power_instance = arc_bridge_service_->power_instance();
+  PowerInstance* power_instance = arc_bridge_service()->power_instance();
   if (!power_instance) {
     LOG(ERROR) << "OnPowerInstanceReady called, but no power instance found";
     return;