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}

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

@@ -6,6 +6,7 @@
 
 #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"
@@ -358,10 +359,13 @@ void AppServiceAppWindowArcTracker::RemoveCandidateWindow(
 }
 
 void AppServiceAppWindowArcTracker::OnItemDelegateDiscarded(
-    const ash::ShelfID& shelf_id) {
+    const ash::ShelfID& shelf_id,
+    ash::ShelfItemDelegate* delegate) {
   arc::ArcAppShelfId app_shelf_id =
       arc::ArcAppShelfId::FromString(shelf_id.app_id);
-  app_shelf_group_to_controller_map_.erase(app_shelf_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);
 }
 
 ash::ShelfID AppServiceAppWindowArcTracker::GetShelfId(int task_id) const {

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

@@ -20,6 +20,10 @@ namespace arc {
 class ArcAppShelfId;
 }
 
+namespace ash {
+class ShelfItemDelegate;
+}
+
 namespace aura {
 class window;
 }
@@ -78,7 +82,8 @@ 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);
+  void OnItemDelegateDiscarded(const ash::ShelfID& shelf_id,
+                               ash::ShelfItemDelegate* delegate);
 
   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());
+      arc_tracker_->OnItemDelegateDiscarded(app_window->shelf_id(), delegate);
 
     if (!app_window || app_window->controller() != delegate)
       continue;