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"
 #include "base/time/time.h"
 #include "components/keyed_service/core/keyed_service.h"
+#include "ui/base/page_transition_types.h"
 
 namespace base {
 class DictionaryValue;
 }
 
 class GURL;
 class Profile;
 
 class SiteEngagementScore {
  public:
   // Keys used in the content settings dictionary.
   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.
+  // The number of points given for navigations.
   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
   // SiteEngagementScore.
@@ skipping 33 matching lines @@
   // any one day.
   base::Time last_engagement_time_;
 
   DISALLOW_COPY_AND_ASSIGN(SiteEngagementScore);
 };
 
 class SiteEngagementScoreProvider {
  public:
   // Returns a non-negative integer representing the engagement score of the
   // origin for this URL.
-  virtual int GetScore(const GURL& url) = 0;
+  virtual double GetScore(const GURL& url) = 0;
 
   // Returns the sum of engagement points awarded to all sites.
-  virtual int GetTotalEngagementPoints() = 0;
+  virtual double GetTotalEngagementPoints() = 0;
 };
 
 // Stores and retrieves the engagement score of an origin.
 //
 // An engagement score is a positive integer that represents how much a user has
 // engaged with an origin - the higher it is, the more engagement the user has
 // had with this site recently.
 //
 // Positive user activity, such as visiting the origin often and adding it to
 // the homescreen, will increase the site engagement score. Negative activity,
 // such as rejecting permission prompts or not responding to notifications, will
 // decrease the site engagement score.
 class SiteEngagementService : public KeyedService,
                               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 navigation.
+  void HandleNavigation(const GURL& url, ui::PageTransition transition);
+
+  // 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;
+  double GetScore(const GURL& url) override;
+  double GetTotalEngagementPoints() override;
 
  private:
+  void AddPoints(const GURL& url, double points);
+
   Profile* profile_;
 
   // The clock used to vend times.
   base::DefaultClock clock_;
 
   DISALLOW_COPY_AND_ASSIGN(SiteEngagementService);
 };
 
 #endif  // CHROME_BROWSER_ENGAGEMENT_SITE_ENGAGEMENT_SERVICE_H_