Making UserClassifier configurable by variation parameters

components/ntp_snippets/user_classifier.h

Index: components/ntp_snippets/user_classifier.h
diff --git a/components/ntp_snippets/user_classifier.h b/components/ntp_snippets/user_classifier.h
index 9ce1c4a3463db9e1d8ac51e0db9cfc8af86745f9..3cdd227edc9c1f3e34e3aa2028683821e80341dc 100644
--- a/components/ntp_snippets/user_classifier.h
+++ b/components/ntp_snippets/user_classifier.h
@@ -91,7 +91,16 @@ class UserClassifier {
   void ClearMetricValue(Metric metric);
 
   PrefService* pref_service_;
+
+  // Params of the metric.
   const double discount_rate_per_hour_;
+  const double min_hours_;
+  const double max_hours_;
+
+  // Params of the classification.
+  const double active_consumer_scrolls_at_least_once_per_hours_;
+  const double active_consumer_opens_ntp_at_least_once_per_hours_;

[Marc Treib, 2016/09/22 12:29:06]

I first wanted to say "s/consumer/user/ to be consistent with the enum", but
this actually described the most-active user class ("active consumer"). I find
that a bit confusing - any reason for introducing another requirement?
Intuitively, the scroll-below-the-fold rate should be sufficient, no?

[jkrcal, 2016/09/22 13:26:15]

Well, I wanted to be on the safe side and have more knobs to control things. You
are right, this is unnecessary complexity.

When we later see that other ways to classify are absolutely necessary, we might
still be able to merge it in M55 Beta. Anyway, classification of active
consumers is not that crucial (as classification of rare users).

+  const double rare_user_opens_ntp_at_most_once_per_hours_;
 
   DISALLOW_COPY_AND_ASSIGN(UserClassifier);
 };