Notify Files App when ARC++ app is installed/removed

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 6d6a25f5fdf87cc191176b86f63f1177cde0239f..478ad5fd2612f2aa40be2a4e2a091801d11c1902 100644
--- a/components/arc/arc_service_manager.cc
+++ b/components/arc/arc_service_manager.cc
@@ -105,6 +105,19 @@ void ArcServiceManager::OnPrimaryUserProfilePrepared(
                                                       account_id));
 }
 
+void ArcServiceManager::AddObserver(Observer* observer) {
+  observer_list_.AddObserver(observer);
+}
+
+void ArcServiceManager::RemoveObserver(Observer* observer) {
+  observer_list_.RemoveObserver(observer);
+}
+
+void ArcServiceManager::OnAppsUpdated() {
+  for (auto& observer : observer_list_)
+    observer.OnAppsUpdated();
+}
+
 void ArcServiceManager::Shutdown() {
   icon_loader_ = nullptr;
   activity_resolver_ = nullptr;