Revert 113315 (speculative revert for http://crbug.com/106657)

base/memory/mru_cache.h

 // Copyright (c) 2011 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.
 
 // This file contains a template for a Most Recently Used cache that allows
 // constant-time access to items using a key, but easy identification of the
 // least-recently-used items for removal.  Each key can only be associated with
 // one payload item at a time.
 //
 // The key object will be stored twice, so it should support efficient copying.
@@ skipping 163 matching lines @@
     return index_.size();
   }
 
   // Allows iteration over the list. Forward iteration starts with the most
   // recent item and works backwards.
   //
   // Note that since these iterators are actually iterators over a list, you
   // can keep them as you insert or delete things (as long as you don't delete
   // the one you are pointing to) and they will still be valid.
   iterator begin() { return ordering_.begin(); }
-  const_iterator begin() const { return ordering_.begin(); }
+  const_iterator begin() const { ordering_.begin(); }
   iterator end() { return ordering_.end(); }
   const_iterator end() const { return ordering_.end(); }
 
   reverse_iterator rbegin() { return ordering_.rbegin(); }
-  const_reverse_iterator rbegin() const { return ordering_.rbegin(); }
+  const_reverse_iterator rbegin() const { ordering_.rbegin(); }
   reverse_iterator rend() { return ordering_.rend(); }
   const_reverse_iterator rend() const { return ordering_.rend(); }
 
   bool empty() const { return ordering_.empty(); }
 
  private:
   PayloadList ordering_;
   KeyIndex index_;
 
   size_type max_size_;
@@ skipping 97 matching lines @@
   virtual ~HashingMRUCache() {
   }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(HashingMRUCache);
 };
 
 }  // namespace base
 
 #endif  // BASE_MEMORY_MRU_CACHE_H_