Implement app list folder management page UI.

ash/test/app_list_controller_test_api.h

Index: ash/test/app_list_controller_test_api.h
diff --git a/ash/test/app_list_controller_test_api.h b/ash/test/app_list_controller_test_api.h
index 3534ffb07d38b757f451445da9b8455c8283e203..4064a7706b36539d4bf63d27d276b568bf90fbb1 100644
--- a/ash/test/app_list_controller_test_api.h
+++ b/ash/test/app_list_controller_test_api.h
@@ -9,6 +9,7 @@
 
 namespace app_list {
 class AppListView;
+class AppsGridView;
 }
 
 namespace ash {
@@ -24,6 +25,9 @@ class AppListControllerTestApi {
  public:
   explicit AppListControllerTestApi(Shell* shell);
 
+  // Gets the root level apps grid view.
+  app_list::AppsGridView* GetRootGridView();
+
   app_list::AppListView* view();
 
  private: