Introduce ArcServiceManager::OnShutdown().

components/arc/arc_service_manager.h

Index: components/arc/arc_service_manager.h
diff --git a/components/arc/arc_service_manager.h b/components/arc/arc_service_manager.h
index cc3dbf6e083726af990d8756bf09ae7d5c938e98..c2c272d8b8cfdb687d719f8d8f2499da3d669fa8 100644
--- a/components/arc/arc_service_manager.h
+++ b/components/arc/arc_service_manager.h
@@ -28,6 +28,11 @@ class ArcServiceManager {
  public:
   class Observer {
    public:
+    // Called when ArcServiceManager is being shut down. Observer
+    // implementation should clean up ARC related stuff here. One of the
+    // typical use cases is calling ArcServiceManager::RemoveObserver().
+    virtual void OnArcShutdown() = 0;
+
     // Called when intent filters are added or removed.
     virtual void OnIntentFiltersUpdated() = 0;
 
@@ -50,12 +55,6 @@ class ArcServiceManager {
   // called on the thread that this class was created on.
   static ArcServiceManager* Get();
 
-  // Returns if the ARC Service Manager instance exists.
-  // DO NOT CALL THIS. This function is a dirty workaround for properly shutting
-  // down chrome/browser/chromeos/extensions/file_manager/event_router.cc, and
-  // will likely be removed in the future.
-  static bool IsInitialized();
-
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);