Fix app list item indexing bug.

ui/app_list/test/app_list_test_view_delegate.h

Index: ui/app_list/test/app_list_test_view_delegate.h
diff --git a/ui/app_list/test/app_list_test_view_delegate.h b/ui/app_list/test/app_list_test_view_delegate.h
index 5cafa04f75baabc63c6762d83be0b90b1ee16463..f7f0dbbbbe51b5fdaf1b55430d9029861af6e8a3 100644
--- a/ui/app_list/test/app_list_test_view_delegate.h
+++ b/ui/app_list/test/app_list_test_view_delegate.h
@@ -31,7 +31,7 @@ class AppListTestViewDelegate : public AppListViewDelegate {
 
   int dismiss_count() { return dismiss_count_; }
   int open_search_result_count() { return open_search_result_count_; }
-  std::map<size_t, int> open_search_result_counts() {
+  std::map<size_t, int>& open_search_result_counts() {
     return open_search_result_counts_;
   }