Add UMA metrics to the site engagement service.

chrome/browser/engagement/site_engagement_service.h

Index: chrome/browser/engagement/site_engagement_service.h
diff --git a/chrome/browser/engagement/site_engagement_service.h b/chrome/browser/engagement/site_engagement_service.h
index de3e9d1024c6bc6aeb92f3a089bfc0c228bc0ed8..0e67b7193bb982ef6326824fa498f8ab7122e5e6 100644
--- a/chrome/browser/engagement/site_engagement_service.h
+++ b/chrome/browser/engagement/site_engagement_service.h
@@ -57,6 +57,10 @@ class SiteEngagementScore {
   double Score() const;
   void AddPoints(double points);
 
+  // Returns true if the maximum number of points today has been added. Resets
+  // the number of points added today if the day has changed.
+  bool MaxPointsPerDayAdded();
+
   // Updates the content settings dictionary |score_dict| with the current score
   // fields. Returns true if |score_dict| changed, otherwise return false.
   bool UpdateScoreDict(base::DictionaryValue* score_dict);
@@ -135,8 +139,19 @@ class SiteEngagementService : public KeyedService,
   double GetTotalEngagementPoints() override;
 
  private:
+  // Adds the specified number of points to the given origin, respecting the
+  // maximum limits for the day and overall.

[calamity, 2015/09/25 07:08:33]

nit: This should be moved into the previous CL but don't worry about it if it's
too annoying.

[dominickn, 2015/09/28 03:34:50]

Done.

   void AddPoints(const GURL& url, double points);
 
+  // Returns the number of origins with maximum daily and total engagement
+  // respectively.
+  int OriginsWithMaxDailyEngagement();
+  int OriginsWithMaxEngagement();
+
+  // Logs the total number of origins stored by the site engagement service, and
+  // the total accumulated engagement score.
+  void RecordStartupUmaStats();
+
   Profile* profile_;
 
   // The clock used to vend times.