[Spellcheck] Add UMA stat for SpellingService

chrome/browser/spellchecker/spellcheck_host_metrics.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 CHROME_BROWSER_SPELLCHECKER_SPELLCHECK_HOST_METRICS_H_
 #define CHROME_BROWSER_SPELLCHECKER_SPELLCHECK_HOST_METRICS_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 37 matching lines @@
   void RecordCheckedWordStats(const string16& word, bool misspell);
 
   // Collects a histogram for misspelled word replacement
   // to be uploaded via UMA
   void RecordReplacedWordStats(int delta);
 
   // Collects a histogram for context menu showing as a spell correction
   // attempt to be uploaded via UMA
   void RecordSuggestionStats(int delta);
 
+  // Records if spelling service is enabled or disabled.
+  void RecordSpellingServiceStats(bool enabled);
+
  private:
   friend class SpellcheckHostMetricsTest;
   void OnHistogramTimerExpired();
 
   // Records various counters without changing their values.
   void RecordWordCounts();
 
   // Number of corrected words of checked words.
   int misspelled_word_count_;
   int last_misspelled_word_count_;
@@ skipping 14 matching lines @@
   int last_unique_word_count_;
 
   // Time when first spellcheck happened.
   base::TimeTicks start_time_;
   // Set of checked words in the hashed form.
   base::hash_set<std::string> checked_word_hashes_;
   base::RepeatingTimer<SpellCheckHostMetrics> recording_timer_;
 };
 
 #endif  // CHROME_BROWSER_SPELLCHECKER_SPELLCHECK_HOST_METRICS_H_