Add ArcAuthService to handle IPC request from ARC

components/arc/arc_bridge_service.cc

Index: components/arc/arc_bridge_service.cc
diff --git a/components/arc/arc_bridge_service.cc b/components/arc/arc_bridge_service.cc
index 3c5f391482c31b691da219c83ac3ec743abceacf..b931c93ce6a2f81be9d103a3ac9f0e4218b673fd 100644
--- a/components/arc/arc_bridge_service.cc
+++ b/components/arc/arc_bridge_service.cc
@@ -62,6 +62,12 @@ void ArcBridgeService::OnAppInstanceReady(AppInstancePtr app_ptr) {
   FOR_EACH_OBSERVER(Observer, observer_list(), OnAppInstanceReady());
 }
 
+void ArcBridgeService::OnAuthInstanceReady(AuthInstancePtr auth_ptr) {
+  DCHECK(CalledOnValidThread());
+  auth_ptr_ = std::move(auth_ptr);
+  FOR_EACH_OBSERVER(Observer, observer_list(), OnAuthInstanceReady());
+}
+
 void ArcBridgeService::OnInputInstanceReady(InputInstancePtr input_ptr) {
   DCHECK(CalledOnValidThread());
   input_ptr_ = std::move(input_ptr);