Implement media playing engagement detection for the site engagement service.

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 <map>
 #include <set>
 
@@ skipping 20 matching lines @@
 
   // The maximum number of points that can be accrued in one day.
   static double g_max_points_per_day;
 
   // The number of points given for navigations.
   static double g_navigation_points;
 
   // The number of points given for user input (indicating time-on-site).
   static double g_user_input_points;
 
+  // The number of points given for media playing. Initially calibrated such
+  // that at least 30 minutes of video watching or audio listening would be
+  // required to allow a site to reach the daily engagement maximum.
+  static double g_visible_media_playing_points;
+
+  // The number of points given for media playing in a non-visible tab.
+  static double g_hidden_media_playing_points;
+
   // Decaying works by removing a portion of the score periodically. This
   // constant determines how often that happens.
   static int g_decay_period_in_days;
 
   // How much the score decays after every kDecayPeriodInDays.
   static double g_decay_points;
 
   // Update the default engagement settings via variations.
   static void UpdateFromVariations();
 
@@ skipping 88 matching lines @@
   std::map<GURL, double> GetScoreMap();
 
   // 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,
                        SiteEngagementMetrics::EngagementType type);
 
+  // Update the karma score of the origin matching |url| for media playing. The
+  // points awarded are discounted if the media is being played in a non-visible
+  // tab.
+  void HandleMediaPlaying(const GURL& url, bool is_hidden);
+
   // Overridden from SiteEngagementScoreProvider:
   double GetScore(const GURL& url) override;
   double GetTotalEngagementPoints() override;
 
  private:
   FRIEND_TEST_ALL_PREFIXES(SiteEngagementServiceTest, CheckHistograms);
   FRIEND_TEST_ALL_PREFIXES(SiteEngagementServiceTest, CleanupEngagementScores);
   FRIEND_TEST_ALL_PREFIXES(SiteEngagementServiceTest, ClearHistoryForURLs);
   FRIEND_TEST_ALL_PREFIXES(SiteEngagementServiceTest, GetMedianEngagement);
   FRIEND_TEST_ALL_PREFIXES(SiteEngagementServiceTest, GetTotalNavigationPoints);
@@ skipping 31 matching lines @@
   // origin's engagement score after an hour has elapsed triggers the next
   // upload.
   base::Time last_metrics_time_;
 
   base::WeakPtrFactory<SiteEngagementService> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SiteEngagementService);
 };
 
 #endif  // CHROME_BROWSER_ENGAGEMENT_SITE_ENGAGEMENT_SERVICE_H_