[remote suggestions] Attach the fetch time to RemoteSnippets, ContentSnippets and SnippetArticle

components/ntp_snippets/content_suggestions_metrics.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/content_suggestions_metrics.h"
 
 #include <cmath>
 #include <string>
 #include <type_traits>
 
@@ skipping 205 matching lines @@
     suggestions_total += item.second;
   }
   UMA_HISTOGRAM_EXACT_LINEAR(kHistogramCountOnNtpOpened, suggestions_total,
                              kMaxSuggestionsTotal);
 }
 
 void OnSuggestionShown(int global_position,
                        Category category,
                        int position_in_category,
                        base::Time publish_date,
-                       base::Time last_background_fetch_time,
-                       float score) {
+                       float score,
+                       base::Time fetch_date) {
   UMA_HISTOGRAM_EXACT_LINEAR(kHistogramShown, global_position,
                              kMaxSuggestionsTotal);
   LogCategoryHistogramPosition(kHistogramShown, category, position_in_category,
                                kMaxSuggestionsPerCategory);
 
   base::TimeDelta age = base::Time::Now() - publish_date;
   LogCategoryHistogramAge(kHistogramShownAge, category, age);
 
   LogCategoryHistogramScore(kHistogramShownScore, category, score);
 
   // TODO(markusheintz): Discuss whether the code below should be move into a
   // separate method called OnSuggestionsListShown.
   // When the first of the articles suggestions is shown, then we count this as
   // a single usage of content suggestions.
   if (category.IsKnownCategory(KnownCategories::ARTICLES) &&
       position_in_category == 0) {
     RecordContentSuggestionsUsage();
 
     // Records the time since the last background fetch of the remote content
     // suggestions.
     UMA_HISTOGRAM_CUSTOM_TIMES(
         kHistogramContentSuggestionsTimeSinceLastBackgroundFetch,
-        base::Time::Now() - last_background_fetch_time,
-        base::TimeDelta::FromSeconds(1), base::TimeDelta::FromDays(7),
+        base::Time::Now() - fetch_date, base::TimeDelta::FromSeconds(1),
+        base::TimeDelta::FromDays(7),
         /*bucket_count=*/100);
   }
 }
 
 void OnSuggestionOpened(int global_position,
                         Category category,
                         int category_index,
                         int position_in_category,
                         base::Time publish_date,
                         float score,
@@ skipping 90 matching lines @@
 }
 
 void OnCategoryDismissed(Category category) {
   UMA_HISTOGRAM_ENUMERATION(kHistogramCategoryDismissed,
                             GetHistogramCategory(category),
                             HistogramCategories::COUNT);
 }
 
 }  // namespace metrics
 }  // namespace ntp_snippets