Fix 'except' and 'prefer' spelling.

chrome/browser/history/history_service.h

 // 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.
 
 #ifndef CHROME_BROWSER_HISTORY_HISTORY_SERVICE_H_
 #define CHROME_BROWSER_HISTORY_HISTORY_SERVICE_H_
 
 #include <set>
 #include <vector>
 
@@ skipping 607 matching lines @@
 
   // Used by FaviconService to find the first favicon bitmap whose width and
   // height are greater than that of |minimum_size_in_pixels|. This searches
   // for icons by IconType. Each element of |icon_types| is a bitmask of
   // IconTypes indicating the types to search for.
   // If the largest icon of |icon_types[0]| is not larger than
   // |minimum_size_in_pixel|, the next icon types of
   // |icon_types| will be searched and so on.
   // If no icon is larger than |minimum_size_in_pixel|, the largest one of all
   // icon types in |icon_types| is returned.
-  // This feature is especially useful when some types of icon is perfered as
+  // This feature is especially useful when some types of icon is preferred as
   // long as its size is larger than a specific value.
   base::CancelableTaskTracker::TaskId GetLargestFaviconForURL(
       const GURL& page_url,
       const std::vector<int>& icon_types,
       int minimum_size_in_pixels,
       const favicon_base::FaviconRawBitmapCallback& callback,
       base::CancelableTaskTracker* tracker);
 
   // Used by the FaviconService to get the favicon bitmap which most closely
   // matches |desired_size| from the favicon with |favicon_id| from the history
@@ skipping 335 matching lines @@
   scoped_ptr<history::InMemoryURLIndex> in_memory_url_index_;
 
   ObserverList<history::VisitDatabaseObserver> visit_database_observers_;
 
   history::DeleteDirectiveHandler delete_directive_handler_;
 
   DISALLOW_COPY_AND_ASSIGN(HistoryService);
 };
 
 #endif  // CHROME_BROWSER_HISTORY_HISTORY_SERVICE_H_