Implement a site engagement score based on time-on-site.

chrome/browser/engagement/site_engagement_service.h

 // Copyright 2015 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_SERVICE_H_
 #define CHROME_BROWSER_ENGAGEMENT_SITE_ENGAGEMENT_SERVICE_H_
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/time/default_clock.h"
@@ skipping 13 matching lines @@
   static const char* kRawScoreKey;
   static const char* kPointsAddedTodayKey;
   static const char* kLastEngagementTimeKey;
 
   // The maximum number of points that are allowed.
   static const double kMaxPoints;
 
   // The maximum number of points that can be accrued in one day.
   static const double kMaxPointsPerDay;
 
-  // The number of points given for a navigation.
-  static const double kNavigationPoints;
+  // The number of points given for user input (indicating time-on-site).
+  static const double kUserInputPoints;
 
   // Decaying works by removing a portion of the score periodically. This
   // constant determines how often that happens.
   static const int kDecayPeriodInDays;
 
   // How much the score decays after every kDecayPeriodInDays.
   static const double kDecayPoints;
 
   // The SiteEngagementService does not take ownership of |clock|. It is the
   // responsibility of the caller to make sure |clock| outlives this
@@ skipping 61 matching lines @@
                               public SiteEngagementScoreProvider {
  public:
   static SiteEngagementService* Get(Profile* profile);
 
   // Returns whether or not the SiteEngagementService is enabled.
   static bool IsEnabled();
 
   explicit SiteEngagementService(Profile* profile);
   ~SiteEngagementService() override;
 
-  // Update the karma score of the origin matching |url| for user navigation.
-  void HandleNavigation(const GURL& url);
+  // Update the karma score of the origin matching |url| for time-on-site, based
+  // on user input.
+  void HandleUserInput(const GURL& url);
 
   // Overridden from SiteEngagementScoreProvider:
   int GetScore(const GURL& url) override;
   int GetTotalEngagementPoints() override;
 
  private:
   Profile* profile_;
 
   // The clock used to vend times.
   base::DefaultClock clock_;
 
   DISALLOW_COPY_AND_ASSIGN(SiteEngagementService);
 };
 
 #endif  // CHROME_BROWSER_ENGAGEMENT_SITE_ENGAGEMENT_SERVICE_H_