Revert "Introduce ArcServiceManager::OnShutdown()."

This reverts commit 772f3e5.

This is for the fixing of crash issue.
Please see details on the linked bug.

BUG=676725
TEST=Ran trybots.

Review-Url: https://codereview.chromium.org/2619203004
Cr-Commit-Position: refs/heads/master@{#442625}

chrome/browser/chromeos/extensions/file_manager/event_router.cc

@@ -401,13 +401,8 @@ EventRouter::EventRouter(Profile* profile)
 
 EventRouter::~EventRouter() = default;
 
-void EventRouter::OnArcShutdown() {
-  DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  arc::ArcServiceManager::Get()->RemoveObserver(this);
-}
-
 void EventRouter::OnIntentFiltersUpdated() {
-  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   BroadcastEvent(profile_,
                  extensions::events::FILE_MANAGER_PRIVATE_ON_APPS_UPDATED,
                  file_manager_private::OnAppsUpdated::kEventName,
@@ -417,6 +412,9 @@ void EventRouter::OnIntentFiltersUpdated() {
 void EventRouter::Shutdown() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
+  if (arc::ArcServiceManager::IsInitialized())
+    arc::ArcServiceManager::Get()->RemoveObserver(this);
+
   chromeos::system::TimezoneSettings::GetInstance()->RemoveObserver(this);
 
   DLOG_IF(WARNING, !file_watchers_.empty())

chrome/browser/chromeos/extensions/file_manager/event_router.h

@@ -68,7 +68,6 @@ class EventRouter : public KeyedService,
   ~EventRouter() override;
 
   // arc::ArcServiceManager::Observer overrides.
-  void OnArcShutdown() override;
   void OnIntentFiltersUpdated() override;
 
   // KeyedService overrides.

chrome/browser/chromeos/note_taking_helper.cc

@@ -181,8 +181,6 @@ void NoteTakingHelper::LaunchAppForNewNote(Profile* profile,
                             static_cast<int>(LaunchResult::MAX));
 }
 
-void NoteTakingHelper::OnArcShutdown() {}
-
 void NoteTakingHelper::OnIntentFiltersUpdated() {
   if (android_enabled_)
     UpdateAndroidApps();

chrome/browser/chromeos/note_taking_helper.h

@@ -151,7 +151,6 @@ class NoteTakingHelper : public arc::ArcServiceManager::Observer,
   void LaunchAppForNewNote(Profile* profile, const base::FilePath& path);
 
   // arc::ArcServiceManager::Observer:
-  void OnArcShutdown() override;
   void OnIntentFiltersUpdated() override;
 
   // arc::ArcSessionManager::Observer:

components/arc/arc_service_manager.cc

@@ -70,6 +70,14 @@ 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();
@@ -92,11 +100,6 @@ 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();

components/arc/arc_service_manager.h

@@ -28,11 +28,6 @@ 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;
 
@@ -55,6 +50,12 @@ 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);