Make Site Engagement behave for adding 0 points.

chrome/browser/engagement/site_engagement_service.cc

 // 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.
 
 #include "chrome/browser/engagement/site_engagement_service.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <utility>
@@ skipping 247 matching lines @@
                                              std::unique_ptr<base::Clock> clock)
     : profile_(profile), clock_(std::move(clock)), weak_factory_(this) {
   // May be null in tests.
   history::HistoryService* history = HistoryServiceFactory::GetForProfile(
       profile, ServiceAccessType::IMPLICIT_ACCESS);
   if (history)
     history->AddObserver(this);
 }
 
 void SiteEngagementService::AddPoints(const GURL& url, double points) {
+  if (points == 0)
+    return;
+
   // Trigger a cleanup and date adjustment if it has been a substantial length
   // of time since *any* engagement was recorded by the service. This will
   // ensure that we do not decay scores when the user did not use the browser.
   if (IsLastEngagementStale())
     CleanupEngagementScores(true);
 
   SiteEngagementScore score = CreateEngagementScore(url);
   score.AddPoints(points);
   score.Commit();
 
@@ skipping 319 matching lines @@
     if (!engagement_score.last_shortcut_launch_time().is_null() &&
         engagement_score.last_shortcut_launch_time() > last_visit) {
       engagement_score.set_last_shortcut_launch_time(last_visit);
     }
 
     engagement_score.Commit();
   }
 
   SetLastEngagementTime(now);
 }