ash: Add support for additional icons in apps search list.

ui/app_list/search_result_observer.h

Index: ui/app_list/search_result_observer.h
diff --git a/ui/app_list/search_result_observer.h b/ui/app_list/search_result_observer.h
index e539c7291de24cb247efbc6eb574b5017a859c61..b78c054613f72ba55fdf188ec1810f66498d2d22 100644
--- a/ui/app_list/search_result_observer.h
+++ b/ui/app_list/search_result_observer.h
@@ -11,9 +11,12 @@ namespace app_list {
 
 class APP_LIST_EXPORT SearchResultObserver {
  public:
-  // Invoked when SearchResult icon has changed.
+  // Invoked when the SearchResult's icon has changed.
   virtual void OnIconChanged() = 0;
 
+  // Invoked when the SearchResult's action icons have been changed.
+  virtual void OnActionIconsChanged() = 0;
+
  protected:
   virtual ~SearchResultObserver() {}
 };