Implement an observer interface for the site engagement service.

chrome/browser/engagement/site_engagement_score.h

 // Copyright 2016 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_ENGAGEMENT_SITE_ENGAGEMENT_SCORE_H_
 #define CHROME_BROWSER_ENGAGEMENT_SITE_ENGAGEMENT_SCORE_H_
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/time/time.h"
@@ skipping 58 matching lines @@
   static double GetDecayPoints();
   static double GetNavigationPoints();
   static double GetUserInputPoints();
   static double GetVisibleMediaPoints();
   static double GetHiddenMediaPoints();
   static double GetWebAppInstalledPoints();
   static double GetFirstDailyEngagementPoints();
   static double GetBootstrapPoints();
   static double GetMediumEngagementBoundary();
   static double GetHighEngagementBoundary();
+  static double GetMinimumEngagementIncrement();
 
   // Update the default engagement settings via variations.
   static void UpdateFromVariations(const char* param_name);
 
   // The SiteEngagementScore does not take ownership of |clock|. It is the
   // responsibility of the caller to make sure |clock| outlives this
   // SiteEngagementScore.
   SiteEngagementScore(base::Clock* clock,
                       const base::DictionaryValue& score_dict);
   ~SiteEngagementScore();
@@ skipping 79 matching lines @@
   base::Time last_engagement_time_;
 
   // The last time the site with this score was launched from an installed
   // shortcut.
   base::Time last_shortcut_launch_time_;
 
   DISALLOW_COPY_AND_ASSIGN(SiteEngagementScore);
 };
 
 #endif  // CHROME_BROWSER_ENGAGEMENT_SITE_ENGAGEMENT_SCORE_H_