Minor refactor to support experiments in AppListMixer.

ui/app_list/search/mixer.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_APP_LIST_SEARCH_MIXER_H_
 #define UI_APP_LIST_SEARCH_MIXER_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 57 matching lines @@
 
   class Group;
   typedef ScopedVector<Group> Groups;
 
   // Publishes the given |new_results| to |ui_results|, deleting any existing
   // results that are not in |new_results|. Results that already exist in
   // |ui_results| are reused to avoid flickering caused by icon reload.
   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);
 
   AppListModel::SearchResults* ui_results_;  // Not owned.
   Groups groups_;
 
   // The ID of the omnibox group. The group with this ID will be treated
   // specially by the Mixer.
   // TODO(mgiuca): Omnibox group should not be treated specially.
   size_t omnibox_group_ = 0;
   // Whether |omnibox_group_| has been set.
   bool has_omnibox_group_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(Mixer);
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_SEARCH_MIXER_H_