Replace AllAppsTileItemView with ArrowExpandView

ui/app_list/views/start_page_view.h

Index: ui/app_list/views/start_page_view.h
diff --git a/ui/app_list/views/start_page_view.h b/ui/app_list/views/start_page_view.h
index 0c4aef3c17a0aa37235076348277a619ce2db0d8..e1df339ced536e2f1064ec8cb2101e7b589cae51 100644
--- a/ui/app_list/views/start_page_view.h
+++ b/ui/app_list/views/start_page_view.h
@@ -19,6 +19,7 @@ class AppListMainView;
 class AppListView;
 class AppListViewDelegate;
 class CustomLauncherPageBackgroundView;
+class ExpandArrowView;
 class IndicatorChipView;
 class SearchResultTileItemView;
 class SuggestionsContainerView;
@@ -79,6 +80,7 @@ class APP_LIST_EXPORT StartPageView : public AppListPage {
   IndicatorChipView* indicator_ = nullptr;  // Owned by views hierarchy.
   SuggestionsContainerView*
       suggestions_container_;  // Owned by views hierarchy.
+  ExpandArrowView* expand_arrow_view_ = nullptr;  // Owned by views hierarchy.
 
   const bool is_fullscreen_app_list_enabled_;