Simplifies the structure of app_list search a bit.

ash/shell/app_list.cc

 // Copyright (c) 2012 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.
 
 #include <string>
 #include <vector>
 
 #include "ash/session/session_state_delegate.h"
 #include "ash/shell.h"
 #include "ash/shell/example_factory.h"
@@ skipping 170 matching lines @@
     base::string16 details =
         base::UTF8ToUTF16(WindowTypeShelfItem::GetDetails(type_));
     set_details(details);
     Tags details_tags;
     details_tags.push_back(Tag(Tag::DIM, 0, details.length()));
     set_details_tags(details_tags);
   }
 
   WindowTypeShelfItem::Type type() const { return type_; }
 
+  // app_list::SearchResult:
+  virtual scoped_ptr<SearchResult> Duplicate() override {
+    return scoped_ptr<SearchResult>();
+  }
+
  private:
   WindowTypeShelfItem::Type type_;
 
   DISALLOW_COPY_AND_ASSIGN(ExampleSearchResult);
 };
 
 class ExampleAppListViewDelegate : public app_list::AppListViewDelegate {
  public:
   ExampleAppListViewDelegate()
       : model_(new app_list::AppListModel) {
@@ skipping 168 matching lines @@
 };
 
 }  // namespace
 
 app_list::AppListViewDelegate* CreateAppListViewDelegate() {
   return new ExampleAppListViewDelegate;
 }
 
 }  // namespace shell
 }  // namespace ash