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

chrome/browser/spellchecker/spellcheck_custom_dictionary.cc

Index: chrome/browser/spellchecker/spellcheck_custom_dictionary.cc
diff --git a/chrome/browser/spellchecker/spellcheck_custom_dictionary.cc b/chrome/browser/spellchecker/spellcheck_custom_dictionary.cc
index 29f89fc2d0a173754acb50347f5abc1b372cced6..6654d68dbe2c6d8640ade6405be35c2275a32238 100644
--- a/chrome/browser/spellchecker/spellcheck_custom_dictionary.cc
+++ b/chrome/browser/spellchecker/spellcheck_custom_dictionary.cc
@@ -448,12 +448,9 @@ void SpellcheckCustomDictionary::Apply(
                   dictionary_change.to_add().end());
   }
   if (!dictionary_change.to_remove().empty()) {
-    WordSet updated_words;
-    std::set_difference(words_.begin(),
-                        words_.end(),
-                        dictionary_change.to_remove().begin(),
-                        dictionary_change.to_remove().end(),
-                        std::inserter(updated_words, updated_words.end()));
+    WordSet updated_words =
+        base::STLSetDifference<WordSet>(words_,
+                                        dictionary_change.to_remove());
     std::swap(words_, updated_words);
   }
 }