Make Site Engagement behave for adding 0 points.

chrome/browser/engagement/site_engagement_service_unittest.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 <utility>
 
 #include "base/files/scoped_temp_dir.h"
 #include "base/macros.h"
@@ skipping 1441 matching lines @@
   base::Time rebased_time = current_day - service->GetMaxDecayPeriod();
   clock->SetNow(current_day);
   service->CleanupEngagementScores(true);
 
   last_engagement_time = base::Time::FromInternalValue(
       profile()->GetPrefs()->GetInt64(prefs::kSiteEngagementLastUpdateTime));
 
   EXPECT_EQ(rebased_time, last_engagement_time);
   EXPECT_EQ(rebased_time, service->GetLastEngagementTime());
 
+  // Adding 0 points shouldn't update the last engagement time.
+  base::Time later_in_day = current_day + base::TimeDelta::FromSeconds(30);
+  clock->SetNow(later_in_day);
+  service->AddPoints(origin, 0);
+
+  last_engagement_time = base::Time::FromInternalValue(
+      profile()->GetPrefs()->GetInt64(prefs::kSiteEngagementLastUpdateTime));
+  EXPECT_EQ(rebased_time, last_engagement_time);
+  EXPECT_EQ(rebased_time, service->GetLastEngagementTime());
+
   // Add some more points and ensure the value is persisted.
-  base::Time later_in_day = current_day + base::TimeDelta::FromSeconds(30);
-  clock->SetNow(later_in_day);
   service->AddPoints(origin, 3);
 
   last_engagement_time = base::Time::FromInternalValue(
       profile()->GetPrefs()->GetInt64(prefs::kSiteEngagementLastUpdateTime));
 
   EXPECT_EQ(later_in_day, last_engagement_time);
   EXPECT_EQ(later_in_day, service->GetLastEngagementTime());
 }
 
 TEST_F(SiteEngagementServiceTest, IncognitoEngagementService) {
@@ skipping 34 matching lines @@
 
   std::map<GURL, double> score_map = incognito_service->GetScoreMap();
   EXPECT_EQ(4u, score_map.size());
   EXPECT_EQ(1, score_map[url1]);
   EXPECT_EQ(3, score_map[url2]);
   EXPECT_EQ(1, score_map[url3]);
   EXPECT_EQ(2, score_map[url4]);
 
   EXPECT_EQ(7, incognito_service->GetTotalEngagementPoints());
 }