app_list::SearchResult: Duplicate() is const.

ui/app_list/test/test_search_result.h

 // Copyright 2014 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_TEST_TEST_SEARCH_RESULT_H_
 #define UI_APP_LIST_TEST_TEST_SEARCH_RESULT_H_
 
 #include "ui/app_list/search_result.h"
 
 namespace app_list {
 
 // A test search result which does nothing.
 class TestSearchResult : public SearchResult {
  public:
   TestSearchResult();
   ~TestSearchResult() override;
 
   // SearchResult:
-  scoped_ptr<SearchResult> Duplicate() override;
+  scoped_ptr<SearchResult> Duplicate() const override;
 
   void SetDisplayType(SearchResult::DisplayType type);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(TestSearchResult);
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_TEST_TEST_SEARCH_RESULT_H_