Minor refactor to support experiments in AppListMixer.

ui/app_list/search/mixer.h

Index: ui/app_list/search/mixer.h
diff --git a/ui/app_list/search/mixer.h b/ui/app_list/search/mixer.h
index 7de0c1141a6926226a561c14d4487b74c7664005..1322057545ce60e1465242cac7326781741fa406 100644
--- a/ui/app_list/search/mixer.h
+++ b/ui/app_list/search/mixer.h
@@ -75,7 +75,10 @@ class APP_LIST_EXPORT Mixer {
   static void Publish(const SortedResults& results,
                       AppListModel::SearchResults* ui_results);
 
-  // Removes duplicates from |results|.
+  // Removes entries from |results| with duplicate IDs. When two or more results
+  // have the same ID, the earliest one in the |results| list is kept.
+  // NOTE: This is not necessarily the one with the highest *score*, as
+  // |results| may not have been sorted yet.
   static void RemoveDuplicates(SortedResults* results);
 
   void FetchResults(bool is_voice_query, const KnownResults& known_results);