[MD History] Fix deletion in heavily scrolled list.

chrome/browser/ui/webui/browsing_history_handler.h

 // Copyright 2015 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 CHROME_BROWSER_UI_WEBUI_BROWSING_HISTORY_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_BROWSING_HISTORY_HANDLER_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 132 matching lines @@
       std::vector<BrowsingHistoryHandler::HistoryEntry>* results);
 
  protected:
   // Callback from the history system when a history query has completed.
   // Exposed for testing.
   void QueryComplete(const base::string16& search_text,
                      const history::QueryOptions& options,
                      history::QueryResults* results);
 
  private:
+  FRIEND_TEST_ALL_PREFIXES(BrowsingHistoryHandlerTest,
+                           ObservingWebHistoryDeletions);
+
   // The range for which to return results:
   // - ALLTIME: allows access to all the results in a paginated way.
   // - WEEK: the last 7 days.
   // - MONTH: the last calendar month.
   enum Range {
     ALL_TIME = 0,
     WEEK = 1,
     MONTH = 2
   };
 
@@ skipping 94 matching lines @@
 
   // Whether there are other forms of browsing history on the history server.
   bool has_other_forms_of_browsing_history_;
 
   base::WeakPtrFactory<BrowsingHistoryHandler> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowsingHistoryHandler);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_BROWSING_HISTORY_HANDLER_H_