Added back button when in folder view.

ui/app_list/views/app_list_view.cc

Index: ui/app_list/views/app_list_view.cc
diff --git a/ui/app_list/views/app_list_view.cc b/ui/app_list/views/app_list_view.cc
index 128b018f2dcde90c6ba3207842482f48d98945ee..98b8e1ceaef445fa43b1cdbf379af445fd4d16e8 100644
--- a/ui/app_list/views/app_list_view.cc
+++ b/ui/app_list/views/app_list_view.cc
@@ -848,6 +848,16 @@ void AppListView::SetState(AppListState new_state) {
       break;
     case FULLSCREEN_ALL_APPS:
       new_widget_bounds.set_y(0);
+      if (app_list_main_view()
+              ->contents_view()
+              ->apps_container_view()
+              ->IsInFolderView()) {
+        app_list_main_view()
+            ->contents_view()
+            ->apps_container_view()

[vadimt, 2017/06/22 18:28:08]

Actually, please create a var for the common part: app_list_main_view()
             ->contents_view()
            ->apps_container_view()

[newcomer, 2017/06/23 23:28:08]

Done.

+            ->app_list_folder_view()
+            ->CloseFolderPage();
+      }
       app_list_main_view_->contents_view()->SetActiveState(
           AppListModel::STATE_APPS);
       break;