app_list: Apps container should not be interactive behind search results

Disables events within apps container subtree when the apps container
is shown (faded) behind search results.

Change-Id: I80e83a584ec206f059e2ab34300d338479e6c6e8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1842008
Commit-Queue: Toni Baržić <tbarzic@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#703086}

ash/app_list/views/apps_container_view.cc

@@ -213,6 +213,10 @@ void AppsContainerView::UpdateControlVisibility(
   if (app_list_state == ash::AppListViewState::kClosed)
     return;
 
+  set_can_process_events_within_subtree(
+      app_list_state == ash::AppListViewState::kFullscreenAllApps ||
+      app_list_state == ash::AppListViewState::kPeeking);
+
   apps_grid_view_->UpdateControlVisibility(app_list_state, is_in_drag);
   page_switcher_->SetVisible(
       is_in_drag ||