[CleanUp] Use base::STLSetDifference in place of std::set_difference

chrome/browser/history/url_index_private_data.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 "chrome/browser/history/url_index_private_data.h"
 
 #include <algorithm>
 #include <functional>
 #include <iterator>
 #include <limits>
@@ skipping 577 matching lines @@
         search_term_cache_[term] = SearchTermCacheItem();
         return HistoryIDSet();
       }
       word_id_set = best_prefix->second.word_id_set_;
       prefix_chars = Char16SetFromString16(best_prefix->first);
       leftovers = term.substr(prefix_length);
     }
 
     // Filter for each remaining, unique character in the term.
     Char16Set leftover_chars = Char16SetFromString16(leftovers);
-    Char16Set unique_chars;
-    std::set_difference(leftover_chars.begin(), leftover_chars.end(),
-                        prefix_chars.begin(), prefix_chars.end(),
-                        std::inserter(unique_chars, unique_chars.begin()));
+    Char16Set unique_chars =
+        base::STLSetDifference<Char16Set>(leftover_chars, prefix_chars);
 
     // Reduce the word set with any leftover, unprocessed characters.
     if (!unique_chars.empty()) {
       WordIDSet leftover_set(WordIDSetForTermChars(unique_chars));
       // We might come up empty on the leftovers.
       if (leftover_set.empty()) {
         search_term_cache_[term] = SearchTermCacheItem();
         return HistoryIDSet();
       }
       // Or there may not have been a prefix from which to start.
@@ skipping 720 matching lines @@
   // recently visited (within the last 12/24 hours) as highly important. Get
   // input from mpearson.
   if (r1.typed_count() != r2.typed_count())
     return (r1.typed_count() > r2.typed_count());
   if (r1.visit_count() != r2.visit_count())
     return (r1.visit_count() > r2.visit_count());
   return (r1.last_visit() > r2.last_visit());
 }
 
 }  // namespace history