Allow AppSearchProvider to provide recommendations.

ui/app_list/app_list_view_delegate.h

Index: ui/app_list/app_list_view_delegate.h
diff --git a/ui/app_list/app_list_view_delegate.h b/ui/app_list/app_list_view_delegate.h
index 606e218251bf81036f1d5a0e0c78bd6aad54b235..32a0a7bd5ca5dfb05c8fad6b61b7b9f8e4f951f1 100644
--- a/ui/app_list/app_list_view_delegate.h
+++ b/ui/app_list/app_list_view_delegate.h
@@ -81,6 +81,10 @@ class APP_LIST_EXPORT AppListViewDelegate {
       const std::string& app_id,
       const base::Callback<void(const base::FilePath&)>& callback) = 0;
 
+  // Invoked to start a search query for recommendations. This populates
+  // AppListModel::SearchResults with the retrieved recommendations.
+  virtual void FetchRecommendations() = 0;
+
   // Invoked to start a new search. Delegate collects query input from
   // SearchBoxModel and populates SearchResults. Both models are sub models
   // of AppListModel.