Revise the comment on base::IDMap::Replace()

base/id_map.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.
 
 #ifndef BASE_ID_MAP_H_
 #define BASE_ID_MAP_H_
 
 #include <stddef.h>
 #include <stdint.h>
 #include <memory>
@@ skipping 63 matching lines @@
       return;
     }
 
     if (iteration_depth_ == 0) {
       data_.erase(i);
     } else {
       removed_ids_.insert(id);
     }
   }
 
-  // Replaces the value for |id| with |new_data| and returns the existing value
-  // (as a unique_ptr<> if in IDMapOwnPointer mode).  Should only be called with
-  // an already added id.
+  // Replaces the value for |id| with |new_data| and returns the existing value.
+  // Should only be called with an already added id.
   V Replace(KeyType id, V new_data) {
     DCHECK(sequence_checker_.CalledOnValidSequence());
     DCHECK(!check_on_null_data_ || new_data);
     typename HashTable::iterator i = data_.find(id);
     DCHECK(i != data_.end());
 
     std::swap(i->second, new_data);
     return new_data;
   }
 
@@ skipping 149 matching lines @@
 
   // See description above setter.
   bool check_on_null_data_;
 
   base::SequenceChecker sequence_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(IDMap);
 };
 
 #endif  // BASE_ID_MAP_H_