Restore KeyedServiceFactory diagnostics for context use-after-destroy.

chrome/browser/engagement/site_engagement_service.h

Index: chrome/browser/engagement/site_engagement_service.h
diff --git a/chrome/browser/engagement/site_engagement_service.h b/chrome/browser/engagement/site_engagement_service.h
index c97eb4abfa7bfa1aaf3887eb7886d66ced363286..8fd5b87b02fb3205598e8dd9f9c4a26f64cfc361 100644
--- a/chrome/browser/engagement/site_engagement_service.h
+++ b/chrome/browser/engagement/site_engagement_service.h
@@ -105,6 +105,9 @@ class SiteEngagementService : public KeyedService,
   explicit SiteEngagementService(Profile* profile);
   ~SiteEngagementService() override;
 
+  // KeyedService support:
+  void Shutdown() override;
+
   // Returns the engagement level of |url|.
   blink::mojom::EngagementLevel GetEngagementLevel(const GURL& url) const;
 
@@ -139,6 +142,7 @@ class SiteEngagementService : public KeyedService,
  private:
   friend class SiteEngagementObserver;
   friend class SiteEngagementServiceAndroid;
+  friend class SiteEngagementServiceTest;
   FRIEND_TEST_ALL_PREFIXES(SiteEngagementServiceTest, CheckHistograms);
   FRIEND_TEST_ALL_PREFIXES(SiteEngagementServiceTest, CleanupEngagementScores);
   FRIEND_TEST_ALL_PREFIXES(SiteEngagementServiceTest,