cros: Fix hanging ShelfButton when showing two menus

This fix does not fix the root cause, but it will prevent the bug from
reproing on M-71.

Root cause fix can be tracked in the same bug.

Bug: 881886
Change-Id: I83882f9d0a5725aad660ea8a6926dd3b689ad306
Reviewed-on: https://chromium-review.googlesource.com/c/1321729Reviewed-by: Michael Wasserman <msw@chromium.org>
Commit-Queue: Alex Newcomer <newcomer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606080}

ash/app_list/views/app_list_item_view.cc

@@ -446,6 +446,7 @@ void AppListItemView::OnContextMenuModelReceived(
     const gfx::Point& point,
     ui::MenuSourceType source_type,
     std::vector<ash::mojom::MenuItemPtr> menu) {
+  waiting_for_context_menu_options_ = false;
   if (menu.empty() || (context_menu_ && context_menu_->IsShowingMenu()))
     return;
 
@@ -490,6 +491,13 @@ void AppListItemView::OnContextMenuModelReceived(
 void AppListItemView::ShowContextMenuForView(views::View* source,
                                              const gfx::Point& point,
                                              ui::MenuSourceType source_type) {
+  // Prevent multiple requests for context menus before the current request
+  // completes. If a second request is sent before the first one can respond,
+  // the Chrome side delegate will become unresponsive
+  // (https://crbug.com/881886).
+  if (waiting_for_context_menu_options_)
+    return;
+  waiting_for_context_menu_options_ = true;
   delegate_->GetContextMenuModel(
       item_weak_->id(),
       base::BindOnce(&AppListItemView::OnContextMenuModelReceived,

ash/app_list/views/app_list_item_view.h

@@ -224,6 +224,10 @@ class APP_LIST_EXPORT AppListItemView
   const bool is_folder_;
   const bool is_in_folder_;
 
+  // Whether context menu options have been requested. Prevents multiple
+  // requests.
+  bool waiting_for_context_menu_options_ = false;
+
   AppListItem* item_weak_;  // Owned by AppListModel. Can be NULL.
 
   AppListViewDelegate* delegate_;            // Unowned.

ash/shelf/shelf_view.cc

@@ -2051,6 +2051,12 @@ void ShelfView::AfterGetContextMenuItems(
 void ShelfView::ShowContextMenuForView(views::View* source,
                                        const gfx::Point& point,
                                        ui::MenuSourceType source_type) {
+  // Prevent multiple requests for context menus before the current request
+  // completes. If a second request is sent before the first one can respond,
+  // the Chrome side ShelfItemDelegate will become unresponsive
+  // (https://crbug.com/881886).
+  if (waiting_for_context_menu_options_)
+    return;
   last_pressed_index_ = -1;
   const ShelfItem* item = ShelfItemForView(source);
   const int64_t display_id = GetDisplayIdForView(this);
@@ -2063,6 +2069,7 @@ void ShelfView::ShowContextMenuForView(views::View* source,
     return;
   }
 
+  waiting_for_context_menu_options_ = true;
   // Get any custom entries; show the context menu in AfterGetContextMenuItems.
   model_->GetShelfItemDelegate(item->id)->GetContextMenuItems(
       display_id, base::Bind(&ShelfView::AfterGetContextMenuItems,
@@ -2076,6 +2083,7 @@ void ShelfView::ShowMenu(std::unique_ptr<ui::SimpleMenuModel> menu_model,
                          bool context_menu,
                          ui::MenuSourceType source_type) {
   DCHECK(!IsShowingMenu());
+  waiting_for_context_menu_options_ = false;
   if (menu_model->GetItemCount() == 0)
     return;
   menu_owner_ = source;

ash/shelf/shelf_view.h

@@ -534,6 +534,10 @@ class ASH_EXPORT ShelfView : public views::View,
   // True when an item being inserted or removed in the model cancels a drag.
   bool cancelling_drag_model_changed_ = false;
 
+  // Whether context menu options have been requested. Prevents multiple
+  // requests.
+  bool waiting_for_context_menu_options_ = false;
+
   // The timestamp of the event which closed the last menu - or 0.
   base::TimeTicks closing_event_time_;