cros: Reset the AppListView focus when it is reshown

When the top window is deactivated, the AppListView is shown without
any preparation. Fix this by resetting the focus and switching to the
first page.

Bug: 951586
Change-Id: I4a39dc503cf6cbee32cf60d29026eac10f3dc84d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1576142
Auto-Submit: Alex Newcomer <newcomer@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Alex Newcomer <newcomer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653651}

ash/app_list/presenter/app_list_presenter_impl.cc

@@ -386,6 +386,7 @@ void AppListPresenterImpl::OnWindowFocused(aura::Window* gained_focus,
         HandleCloseOpenSearchBox();
       } else if (applist_window->Contains(gained_focus)) {
         home_launcher_shown_ = true;
+        view_->ResetForShow();
       }
     }
 

ash/app_list/views/app_list_view.cc

@@ -452,6 +452,16 @@ void AppListView::Dismiss() {
   GetWidget()->Deactivate();
 }
 
+void AppListView::ResetForShow() {
+  if (GetFocusManager()->GetFocusedView() != GetInitiallyFocusedView())
+    GetInitiallyFocusedView()->RequestFocus();
+
+  if (GetAppsPaginationModel()->total_pages() > 0 &&
+      GetAppsPaginationModel()->selected_page() != 0) {
+    GetAppsPaginationModel()->SelectPage(0, false /* animate */);
+  }
+}
+
 void AppListView::CloseOpenedPage() {
   if (HandleCloseOpenFolder())
     return;

ash/app_list/views/app_list_view.h

@@ -150,6 +150,9 @@ class APP_LIST_EXPORT AppListView : public views::WidgetDelegateView,
   // Dismisses the UI, cleans up and sets the state to CLOSED.
   void Dismiss();
 
+  // Resets the child views before showing the AppListView.
+  void ResetForShow();
+
   // Closes opened folder or search result page if they are opened.
   void CloseOpenedPage();