Add a skeleton Start Page to the experimental app list.

ui/app_list/views/app_list_main_view.cc

Index: ui/app_list/views/app_list_main_view.cc
diff --git a/ui/app_list/views/app_list_main_view.cc b/ui/app_list/views/app_list_main_view.cc
index b6255a0e4eec10460decf4829543adbd4f8a6c4f..221501a6783b582f2d8e94370a5506e0df540506 100644
--- a/ui/app_list/views/app_list_main_view.cc
+++ b/ui/app_list/views/app_list_main_view.cc
@@ -165,6 +165,11 @@ void AppListMainView::ModelChanged() {
   Layout();
 }
 
+void AppListMainView::OnContentsViewShowStateChanged(
+    ContentsView::ShowState show_state) {
+  search_box_view_->SetVisible(show_state != ContentsView::SHOW_START_PAGE);
+}
+
 void AppListMainView::SetDragAndDropHostOfCurrentAppList(
     ApplicationDragAndDropHost* drag_and_drop_host) {
   contents_view_->SetDragAndDropHostOfCurrentAppList(drag_and_drop_host);