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..87c69026485ec2a87642ec11b30685c7a064b7b2 100644
--- a/ui/app_list/views/app_list_main_view.cc
+++ b/ui/app_list/views/app_list_main_view.cc
@@ -22,7 +22,6 @@
 #include "ui/app_list/views/app_list_item_view.h"
 #include "ui/app_list/views/apps_container_view.h"
 #include "ui/app_list/views/contents_switcher_view.h"
-#include "ui/app_list/views/contents_view.h"
 #include "ui/app_list/views/search_box_view.h"
 #include "ui/views/controls/textfield/textfield.h"
 #include "ui/views/layout/box_layout.h"
@@ -165,6 +164,11 @@ 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);