Revert "Fix the issue that ARC app can't start from shelf after switch users."

This reverts commit 2359557a.

Reason for revert: heap-buffer-overflow found by ASAN bot, likely due to accessing std::map<>::end() returned by std::map<>::find().

Original change's description:
> Fix the issue that ARC app can't start from shelf after switch users.
> 
> The reason is that OnItemDelegateDiscarded is called, and the
> controller is deleted from app_shelf_group_to_controller_map_, even
> though the parameter delegate is not the controller saved in
> app_shelf_group_to_controller_map_. So adding a checking in
> OnItemDelegateDiscarded, only when the parameter delegate is the
> controller saved in app_shelf_group_to_controller_map_, delete it,
> otherwise, don't delete the controller in
> app_shelf_group_to_controller_map_.
> 
> BUG=1011235
> 
> Change-Id: I300b5fc4a46b9441a063c34bac745a5018aa5b82
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1976140
> Commit-Queue: Nancy Wang <nancylingwang@chromium.org>
> Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#726710}

TBR=xiyuan@chromium.org,nancylingwang@chromium.org

Change-Id: I3c8ee654bd33b2a5235815c01ad6ed1957309c0c
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1011235
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1979539Reviewed-by: Samuel Huang <huangs@chromium.org>
Commit-Queue: Samuel Huang <huangs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#727034}

chrome/browser/ui/ash/launcher/app_service/app_service_app_window_arc_tracker.cc

@@ -6,7 +6,6 @@
 
 #include "ash/public/cpp/app_types.h"
 #include "ash/public/cpp/multi_user_window_manager.h"
-#include "ash/public/cpp/shelf_item_delegate.h"
 #include "ash/public/cpp/shelf_model.h"
 #include "ash/public/cpp/shelf_types.h"
 #include "ash/public/cpp/window_properties.h"
@@ -359,13 +358,10 @@ void AppServiceAppWindowArcTracker::RemoveCandidateWindow(
 }
 
 void AppServiceAppWindowArcTracker::OnItemDelegateDiscarded(
-    const ash::ShelfID& shelf_id,
-    ash::ShelfItemDelegate* delegate) {
+    const ash::ShelfID& shelf_id) {
   arc::ArcAppShelfId app_shelf_id =
       arc::ArcAppShelfId::FromString(shelf_id.app_id);
-  auto it = app_shelf_group_to_controller_map_.find(app_shelf_id);
-  if (static_cast<ash::ShelfItemDelegate*>(it->second) == delegate)
-    app_shelf_group_to_controller_map_.erase(app_shelf_id);
+  app_shelf_group_to_controller_map_.erase(app_shelf_id);
 }
 
 ash::ShelfID AppServiceAppWindowArcTracker::GetShelfId(int task_id) const {

chrome/browser/ui/ash/launcher/app_service/app_service_app_window_arc_tracker.h

@@ -20,10 +20,6 @@ namespace arc {
 class ArcAppShelfId;
 }
 
-namespace ash {
-class ShelfItemDelegate;
-}
-
 namespace aura {
 class window;
 }
@@ -82,8 +78,7 @@ class AppServiceAppWindowArcTracker : public ArcAppListPrefs::Observer,
   void RemoveCandidateWindow(aura::Window* window);
 
   // Removes controller from |app_shelf_group_to_controller_map_|.
-  void OnItemDelegateDiscarded(const ash::ShelfID& shelf_id,
-                               ash::ShelfItemDelegate* delegate);
+  void OnItemDelegateDiscarded(const ash::ShelfID& shelf_id);
 
   ash::ShelfID GetShelfId(int task_id) const;
 

chrome/browser/ui/ash/launcher/app_service/app_service_app_window_launcher_controller.cc

@@ -498,7 +498,7 @@ void AppServiceAppWindowLauncherController::OnItemDelegateDiscarded(
       continue;
 
     if (arc_tracker_)
-      arc_tracker_->OnItemDelegateDiscarded(app_window->shelf_id(), delegate);
+      arc_tracker_->OnItemDelegateDiscarded(app_window->shelf_id());
 
     if (!app_window || app_window->controller() != delegate)
       continue;