Add a histogram for recording content suggestions local usage time stats.

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 <string>
 #include <type_traits>
 
 #include "base/metrics/histogram.h"
@@ skipping 22 matching lines @@
     "NewTabPage.ContentSuggestions.OpenDisposition";
 const char kHistogramMenuOpened[] = "NewTabPage.ContentSuggestions.MenuOpened";
 const char kHistogramMenuOpenedAge[] =
     "NewTabPage.ContentSuggestions.MenuOpenedAge";
 const char kHistogramMenuOpenedScore[] =
     "NewTabPage.ContentSuggestions.MenuOpenedScore";
 const char kHistogramDismissedUnvisited[] =
     "NewTabPage.ContentSuggestions.DismissedUnvisited";
 const char kHistogramDismissedVisited[] =
     "NewTabPage.ContentSuggestions.DismissedVisited";
+const char kHistogramUsageTimeLocal[] =
+    "NewTabPage.ContentSuggestions.UsageTimeLocal";
 const char kHistogramVisitDuration[] =
     "NewTabPage.ContentSuggestions.VisitDuration";
 const char kHistogramMoreButtonShown[] =
     "NewTabPage.ContentSuggestions.MoreButtonShown";
 const char kHistogramMoreButtonClicked[] =
     "NewTabPage.ContentSuggestions.MoreButtonClicked";
 
 const char kPerCategoryHistogramFormat[] = "%s.%s";
 
-// Each suffix here should correspond to an entry under histogram suffix
-// ContentSuggestionCategory in histograms.xml.
-std::string GetCategorySuffix(Category category) {
+// Returns the KnownCategory value for the given Category.
+KnownCategories GetKnownCategory(Category category) {

[Marc Treib, 2016/11/16 16:00:55]

Per the comments below, this isn't necessary. (I wouldn't like to pass around a
KnownCategories instance that isn't necessarily one of the actual values...)

[markusheintz_, 2016/11/16 16:09:42]

Done.

   static_assert(
       std::is_same<decltype(category.id()), typename base::underlying_type<
                                                 KnownCategories>::type>::value,
       "KnownCategories must have the same underlying type as category.id()");
   // Note: Since the underlying type of KnownCategories is int, it's legal to
   // cast from int to KnownCategories, even if the given value isn't listed in
   // the enumeration. The switch still makes sure that all known values are
   // listed here.
-  KnownCategories known_category = static_cast<KnownCategories>(category.id());
+  return static_cast<KnownCategories>(category.id());
+}
+
+// Each suffix here should correspond to an entry under histogram suffix
+// ContentSuggestionCategory in histograms.xml.
+std::string GetCategorySuffix(Category category) {
+  KnownCategories known_category = GetKnownCategory(category);
   switch (known_category) {
     case KnownCategories::RECENT_TABS:
       return "RecentTabs";
     case KnownCategories::DOWNLOADS:
       return "Downloads";
     case KnownCategories::BOOKMARKS:
       return "Bookmarks";
     case KnownCategories::PHYSICAL_WEB_PAGES:
       return "PhysicalWeb";
     case KnownCategories::FOREIGN_TABS:
@@ skipping 78 matching lines @@
 }
 
 void LogCategoryHistogramScore(const char* base_name,
                                Category category,
                                float score) {
   std::string name = GetCategoryHistogramName(base_name, category);
   // Since the histogram name is dynamic, we can't use the regular macro.
   UmaHistogramScore(name, score);
 }
 
+// Records ContentSuggestions usage. Therefore the day is sliced into 20min
+// buckets. Depending on the current local time the count of the corresponding
+// bucket is increased.
+void RecordContentSuggestionsUsage() {
+  const int kBucketSizeMins = 20;
+  const int kNumBuckets = 24 * 60 / kBucketSizeMins;
+
+  base::Time::Exploded now_exploded;
+  base::Time::Now().LocalExplode(&now_exploded);
+  size_t bucket =
+      (now_exploded.hour * 60 + now_exploded.minute) / kBucketSizeMins;
+
+  UMA_HISTOGRAM_ENUMERATION(kHistogramUsageTimeLocal, bucket, kNumBuckets);
+}
+
 }  // namespace
 
 void OnPageShown(
     const std::vector<std::pair<Category, int>>& suggestions_per_category) {
   int suggestions_total = 0;
   for (const std::pair<Category, int>& item : suggestions_per_category) {
     LogCategoryHistogramEnumeration(kHistogramCountOnNtpOpened, item.first,
                                     item.second, kMaxSuggestionsPerCategory);
     suggestions_total += item.second;
   }
 
   UMA_HISTOGRAM_ENUMERATION(kHistogramCountOnNtpOpened, suggestions_total,
                             kMaxSuggestionsTotal);
 }
 
 void OnSuggestionShown(int global_position,
                        Category category,
                        int category_position,
                        base::Time publish_date,
                        float score) {
   UMA_HISTOGRAM_ENUMERATION(kHistogramShown, global_position,
                             kMaxSuggestionsTotal);
   LogCategoryHistogramEnumeration(kHistogramShown, category, category_position,
                                   kMaxSuggestionsPerCategory);
 
   base::TimeDelta age = base::Time::Now() - publish_date;
   LogCategoryHistogramAge(kHistogramShownAge, category, age);
 
   LogCategoryHistogramScore(kHistogramShownScore, category, score);
+
+  // When the first of all suggestions is shown, then we count this as a

[Marc Treib, 2016/11/16 16:00:55]

nit: Now it's not the first of all suggestions anymore :)

[markusheintz_, 2016/11/16 16:09:42]

Done.

+  // single usage of content suggestions.
+  if (GetKnownCategory(category) == KnownCategories::ARTICLES &&

[Marc Treib, 2016/11/16 16:00:55]

category.IsKnownCategory(KnownCategories::ARTICLES)

[markusheintz_, 2016/11/16 16:09:42]

Done.

+      category_position == 0) {
+    RecordContentSuggestionsUsage();
+  }
 }
 
 void OnSuggestionOpened(int global_position,
                         Category category,
                         int category_position,
                         base::Time publish_date,
                         float score,
                         WindowOpenDisposition disposition) {
   UMA_HISTOGRAM_ENUMERATION(kHistogramOpened, global_position,
                             kMaxSuggestionsTotal);
   LogCategoryHistogramEnumeration(kHistogramOpened, category, category_position,
                                   kMaxSuggestionsPerCategory);
 
   base::TimeDelta age = base::Time::Now() - publish_date;
   LogCategoryHistogramAge(kHistogramOpenedAge, category, age);
 
   LogCategoryHistogramScore(kHistogramOpenedScore, category, score);
 
   UMA_HISTOGRAM_ENUMERATION(
       kHistogramOpenDisposition, static_cast<int>(disposition),
       static_cast<int>(WindowOpenDisposition::MAX_VALUE) + 1);
   LogCategoryHistogramEnumeration(
       kHistogramOpenDisposition, category, static_cast<int>(disposition),
       static_cast<int>(WindowOpenDisposition::MAX_VALUE) + 1);
+
+  if (GetKnownCategory(category) == KnownCategories::ARTICLES) {

[Marc Treib, 2016/11/16 16:00:55]

Also here:
category.IsKnownCategory(KnownCategories::ARTICLES)

[markusheintz_, 2016/11/16 16:09:42]

Done.

+    RecordContentSuggestionsUsage();
+  }
 }
 
 void OnSuggestionMenuOpened(int global_position,
                             Category category,
                             int category_position,
                             base::Time publish_date,
                             float score) {
   UMA_HISTOGRAM_ENUMERATION(kHistogramMenuOpened, global_position,
                             kMaxSuggestionsTotal);
   LogCategoryHistogramEnumeration(kHistogramMenuOpened, category,
@@ skipping 38 matching lines @@
 
 void OnMoreButtonClicked(Category category, int position) {
   // The "more" card can appear in addition to the actual suggestions, so add
   // one extra bucket to this histogram.
   LogCategoryHistogramEnumeration(kHistogramMoreButtonClicked, category,
                                   position, kMaxSuggestionsPerCategory + 1);
 }
 
 }  // namespace metrics
 }  // namespace ntp_snippets