Connecting UserClassifier to NtpSnippetsFetcher

components/ntp_snippets/user_classifier.cc

 // Copyright 2016 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 "components/ntp_snippets/user_classifier.h"
 
 #include <algorithm>
 #include <cfloat>
 #include <string>
 
@@ skipping 249 matching lines @@
 }
 
 double UserClassifier::GetEstimatedAvgTime(Metric metric) const {
   DCHECK_NE(metric, Metric::COUNT);
   double metric_value = GetUpToDateMetricValue(metric);
   return GetEstimateHoursBetweenEvents(metric_value, discount_rate_per_hour_,
                                        min_hours_, max_hours_);
 }
 
 UserClassifier::UserClass UserClassifier::GetUserClass() const {
+  // The pref_service_ can be null in tests.
+  if (!pref_service_)

[Marc Treib, 2016/10/06 14:54:37]

Is this necessary? All things being equal, I prefer to avoid "null in tests".

[jkrcal, 2016/10/06 15:18:41]

If the pref_service is null, we anyway get some default value (based on default
values deeper in the calls), it is just very unclear what it is. If you insist,
I can remove it.

[Marc Treib, 2016/10/06 15:27:26]

Ah, I just noticed that there's lots of other null checks for the pref_service_
in this class... no, then one more doesn't matter. For the future, it'd be nice
if we could get rid of them all. It's fairly simple to pass in a fake pref
service in tests.

[jkrcal, 2016/10/06 18:25:38]

Makes sense...

+    return UserClass::ACTIVE_NTP_USER;
+
   if (GetEstimatedAvgTime(Metric::NTP_OPENED) >=
       rare_user_opens_ntp_at_most_once_per_hours_) {
     return UserClass::RARE_NTP_USER;
   }
 
   if (GetEstimatedAvgTime(Metric::SUGGESTIONS_SHOWN) <=
       active_consumer_scrolls_at_least_once_per_hours_) {
     return UserClass::ACTIVE_SUGGESTIONS_CONSUMER;
   }
 
@@ skipping 84 matching lines @@
 
 void UserClassifier::SetMetricValue(Metric metric, double metric_value) {
   pref_service_->SetDouble(kMetricKeys[static_cast<int>(metric)], metric_value);
 }
 
 void UserClassifier::ClearMetricValue(Metric metric) {
   pref_service_->ClearPref(kMetricKeys[static_cast<int>(metric)]);
 }
 
 }  // namespace ntp_snippets