Measure usage metrics to prepare for adaptive fetching rates in M55

components/ntp_snippets/pref_names.cc

Index: components/ntp_snippets/pref_names.cc
diff --git a/components/ntp_snippets/pref_names.cc b/components/ntp_snippets/pref_names.cc
index 4221d60082acf7625a499fb94496a95ee74be955..08b2b4ede132d073dd884ecc46ac9eefb1876f58 100644
--- a/components/ntp_snippets/pref_names.cc
+++ b/components/ntp_snippets/pref_names.cc
@@ -33,5 +33,20 @@ const char kDismissedDownloadSuggestions[] =
 const char kBookmarksFirstM54Start[] =
     "ntp_suggestions.bookmarks.first_M54_start";
 
+const char kUserClassifierAverageHoursToOpenNTP[] =
+    "ntp_suggestions.user_classifier.average_hours_to_open_ntp";
+const char kUserClassifierAverageHoursToShowSuggestions[] =
+    "ntp_suggestions.user_classifier.average_hours_to_show_suggestions";
+const char kUserClassifierAverageHoursToUseSuggestions[] =
+    "ntp_suggestions.user_classifier.average_hours_to_use_suggestions";
+
+const char kUserClassifierLastTimeToOpenNTP[] =
+    "ntp_suggestions.user_classifier.last_time_to_open_ntp";
+const char kUserClassifierLastTimeToShowSuggestions[] =
+    "ntp_suggestions.user_classifier.last_time_to_show_suggestions";
+const char kUserClassifierLastTimeToUseSuggestions[] =
+    "ntp_suggestions.user_classifier.last_time_to_use_suggestions";
+
+
 }  // namespace prefs
 }  // namespace ntp_snippets