[Spellcheck] Add UMA stat for SpellingService

chrome/browser/spellchecker/spellcheck_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_SPELLCHECKER_SPELLCHECK_SERVICE_H_
 #define CHROME_BROWSER_SPELLCHECKER_SPELLCHECK_SERVICE_H_
 
 #include "base/gtest_prod_util.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 103 matching lines @@
   void InitForAllRenderers();
 
   // Reacts to a change in user preferences on whether auto-spell-correct should
   // be enabled.
   void OnEnableAutoSpellCorrectChanged();
 
   // Reacts to a change in user preference on which language should be used for
   // spellchecking.
   void OnSpellCheckDictionaryChanged();
 
+  // Notification handler for changes to prefs::kSpellCheckUseSpellingService.
+  void OnUseSpellingServiceChanged();
+
   PrefChangeRegistrar pref_change_registrar_;
   content::NotificationRegistrar registrar_;
 
   // A pointer to the profile which this service refers to.
   Profile* profile_;
 
   scoped_ptr<SpellCheckHostMetrics> metrics_;
 
   scoped_ptr<SpellcheckCustomDictionary> custom_dictionary_;
 
   scoped_ptr<SpellcheckHunspellDictionary> hunspell_dictionary_;
 
   base::WeakPtrFactory<SpellcheckService> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SpellcheckService);
 };
 
 #endif  // CHROME_BROWSER_SPELLCHECKER_SPELLCHECK_SERVICE_H_