Make the site engagement service more robust to clock changes and time inconsistencies.

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 <memory>
 #include <set>
@@ skipping 120 matching lines @@
 
   // Overridden from SiteEngagementScoreProvider.
   double GetScore(const GURL& url) const override;
   double GetTotalEngagementPoints() const override;
 
  private:
   friend class SiteEngagementObserver;
   FRIEND_TEST_ALL_PREFIXES(SiteEngagementServiceTest, CheckHistograms);
   FRIEND_TEST_ALL_PREFIXES(SiteEngagementServiceTest, CleanupEngagementScores);
   FRIEND_TEST_ALL_PREFIXES(SiteEngagementServiceTest,
+                           CleanupMovesScoreBackToNow);
+  FRIEND_TEST_ALL_PREFIXES(SiteEngagementServiceTest,
+                           CleanupMovesScoreBackToRebase);
+  FRIEND_TEST_ALL_PREFIXES(SiteEngagementServiceTest,
                            CleanupEngagementScoresProportional);
   FRIEND_TEST_ALL_PREFIXES(SiteEngagementServiceTest, ClearHistoryForURLs);
   FRIEND_TEST_ALL_PREFIXES(SiteEngagementServiceTest, GetMedianEngagement);
   FRIEND_TEST_ALL_PREFIXES(SiteEngagementServiceTest, GetTotalNavigationPoints);
   FRIEND_TEST_ALL_PREFIXES(SiteEngagementServiceTest, GetTotalUserInputPoints);
   FRIEND_TEST_ALL_PREFIXES(SiteEngagementServiceTest, LastShortcutLaunch);
   FRIEND_TEST_ALL_PREFIXES(SiteEngagementServiceTest,
                            CleanupOriginsOnHistoryDeletion);
   FRIEND_TEST_ALL_PREFIXES(SiteEngagementServiceTest, IsBootstrapped);
   FRIEND_TEST_ALL_PREFIXES(SiteEngagementServiceTest, EngagementLevel);
@@ skipping 104 matching lines @@
   // A list of observers. When any origin registers an engagement-increasing
   // event, each observer's OnEngagementIncreased method will be called.
   base::ObserverList<SiteEngagementObserver> observer_list_;
 
   base::WeakPtrFactory<SiteEngagementService> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SiteEngagementService);
 };
 
 #endif  // CHROME_BROWSER_ENGAGEMENT_SITE_ENGAGEMENT_SERVICE_H_