Introduce ArcServiceManager::OnShutdown().

components/arc/arc_service_manager.cc

Index: components/arc/arc_service_manager.cc
diff --git a/components/arc/arc_service_manager.cc b/components/arc/arc_service_manager.cc
index e07cb955cb15b4f47a685a5d17cbaae369807d81..dc8aec789b5e93e7b19bb76b8e6902f633de3bca 100644
--- a/components/arc/arc_service_manager.cc
+++ b/components/arc/arc_service_manager.cc
@@ -83,14 +83,6 @@ ArcServiceManager* ArcServiceManager::Get() {
   return g_arc_service_manager;
 }
 
-// static
-bool ArcServiceManager::IsInitialized() {
-  if (!g_arc_service_manager)
-    return false;
-  DCHECK(g_arc_service_manager->thread_checker_.CalledOnValidThread());
-  return true;
-}
-
 ArcBridgeService* ArcServiceManager::arc_bridge_service() {
   DCHECK(thread_checker_.CalledOnValidThread());
   return arc_bridge_service_.get();
@@ -113,6 +105,11 @@ void ArcServiceManager::RemoveObserver(Observer* observer) {
 
 void ArcServiceManager::Shutdown() {
   DCHECK(thread_checker_.CalledOnValidThread());
+
+  // Before actual shutdown, notify observers for clean up.
+  for (auto& observer : observer_list_)
+    observer.OnArcShutdown();
+
   icon_loader_ = nullptr;
   activity_resolver_ = nullptr;
   services_.clear();