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..cb948e68fa814c34fb8aabf6a6550ca1e25c0cec 100644
--- a/ui/app_list/views/app_list_view.cc
+++ b/ui/app_list/views/app_list_view.cc
@@ -846,11 +846,18 @@ void AppListView::SetState(AppListState new_state) {
           break;
       }
       break;
-    case FULLSCREEN_ALL_APPS:
+    case FULLSCREEN_ALL_APPS: {
       new_widget_bounds.set_y(0);
+      AppsContainerView* apps_container_view =
+          app_list_main_view_->contents_view()->apps_container_view();
+
+      if (apps_container_view->IsInFolderView()) {
+        apps_container_view->app_list_folder_view()->CloseFolderPage();
+      }
       app_list_main_view_->contents_view()->SetActiveState(
           AppListModel::STATE_APPS);
-      break;
+    }
+    break;
     case FULLSCREEN_SEARCH:
       new_widget_bounds.set_y(0);
       break;