Allow SiteEngagementService::IsEnabled to respect field trial groups.

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 <algorithm>
 #include <cmath>
 #include <vector>
 
 #include "base/command_line.h"
+#include "base/metrics/field_trial.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/time/clock.h"
 #include "base/time/default_clock.h"
 #include "base/values.h"
 #include "chrome/browser/content_settings/host_content_settings_map_factory.h"
 #include "chrome/browser/engagement/site_engagement_helper.h"
 #include "chrome/browser/engagement/site_engagement_service_factory.h"
 #include "chrome/common/chrome_switches.h"
 #include "components/content_settings/core/browser/host_content_settings_map.h"
 #include "components/content_settings/core/common/content_settings_pattern.h"
@@ skipping 225 matching lines @@
   return std::max(0.0, decayed_score);
 }
 
 // static
 SiteEngagementService* SiteEngagementService::Get(Profile* profile) {
   return SiteEngagementServiceFactory::GetForProfile(profile);
 }
 
 // static
 bool SiteEngagementService::IsEnabled() {
-  return base::CommandLine::ForCurrentProcess()->HasSwitch(
-      switches::kEnableSiteEngagementService);
+  const std::string group_name =
+      base::FieldTrialList::FindFullName(kEngagementParams);
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableSiteEngagementService)) {
+    return true;
+  }
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kDisableSiteEngagementService)) {
+    return false;
+  }
+  return base::StartsWith(group_name, "Enabled", base::CompareCase::SENSITIVE);
 }
 
 // static
 void SiteEngagementService::ClearHistoryForURLs(Profile* profile,
                                                 const std::set<GURL>& origins) {
   HostContentSettingsMap* settings_map =
       HostContentSettingsMapFactory::GetForProfile(profile);
 
   for (const GURL& origin_url : origins) {
     ContentSettingsPattern pattern(
@@ skipping 216 matching lines @@
 int SiteEngagementService::OriginsWithMaxEngagement(
     std::map<GURL, double>& score_map) {
   int total_origins = 0;
 
   for (const auto& value : score_map)
     if (value.second == SiteEngagementScore::kMaxPoints)
       ++total_origins;
 
   return total_origins;
 }