Log suggestion scores in 10 discrete buckets.

components/ntp_snippets/content_suggestions_metrics.cc

Index: components/ntp_snippets/content_suggestions_metrics.cc
diff --git a/components/ntp_snippets/content_suggestions_metrics.cc b/components/ntp_snippets/content_suggestions_metrics.cc
index 4f61eed1fa9af77c9dbb0f6ea8386caaae14bbf1..493f8c0672e7c7f99da83f19919b1c7b90c3aefd 100644
--- a/components/ntp_snippets/content_suggestions_metrics.cc
+++ b/components/ntp_snippets/content_suggestions_metrics.cc
@@ -4,10 +4,12 @@
 
 #include "components/ntp_snippets/content_suggestions_metrics.h"
 
+#include <cmath>
 #include <string>
 #include <type_traits>
 
 #include "base/metrics/histogram.h"
+#include "base/metrics/histogram_functions.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/user_metrics.h"
 #include "base/strings/stringprintf.h"
@@ -25,18 +27,19 @@ const char kHistogramCountOnNtpOpened[] =
     "NewTabPage.ContentSuggestions.CountOnNtpOpened";
 const char kHistogramShown[] = "NewTabPage.ContentSuggestions.Shown";
 const char kHistogramShownAge[] = "NewTabPage.ContentSuggestions.ShownAge";
-const char kHistogramShownScore[] = "NewTabPage.ContentSuggestions.ShownScore";
+const char kHistogramShownScore[] =
+    "NewTabPage.ContentSuggestions.ShownScoreNormalized";
 const char kHistogramOpened[] = "NewTabPage.ContentSuggestions.Opened";
 const char kHistogramOpenedAge[] = "NewTabPage.ContentSuggestions.OpenedAge";
 const char kHistogramOpenedScore[] =
-    "NewTabPage.ContentSuggestions.OpenedScore";
+    "NewTabPage.ContentSuggestions.OpenedScoreNormalized";
 const char kHistogramOpenDisposition[] =
     "NewTabPage.ContentSuggestions.OpenDisposition";
 const char kHistogramMenuOpened[] = "NewTabPage.ContentSuggestions.MenuOpened";
 const char kHistogramMenuOpenedAge[] =
     "NewTabPage.ContentSuggestions.MenuOpenedAge";
 const char kHistogramMenuOpenedScore[] =
-    "NewTabPage.ContentSuggestions.MenuOpenedScore";
+    "NewTabPage.ContentSuggestions.MenuOpenedScoreNormalized";
 const char kHistogramDismissedUnvisited[] =
     "NewTabPage.ContentSuggestions.DismissedUnvisited";
 const char kHistogramDismissedVisited[] =
@@ -60,7 +63,7 @@ const char kPerCategoryHistogramFormat[] = "%s.%s";
 // and contains exactly the values to be recorded in UMA. Don't remove or
 // reorder elements, only add new ones at the end (before COUNT), and keep in
 // sync with ContentSuggestionsCategory in histograms.xml.
-enum class HistogramCategories {
+enum HistogramCategories {
   EXPERIMENTAL,
   RECENT_TABS,
   DOWNLOADS,
@@ -135,27 +138,6 @@ std::string GetCategoryHistogramName(const char* base_name, Category category) {
                             GetCategorySuffix(category).c_str());
 }
 
-// This corresponds to UMA_HISTOGRAM_ENUMERATION, for use with dynamic histogram
-// names.
-void UmaHistogramEnumeration(const std::string& name,
-                             int value,
-                             int boundary_value) {
-  base::LinearHistogram::FactoryGet(
-      name, 1, boundary_value, boundary_value + 1,
-      base::HistogramBase::kUmaTargetedHistogramFlag)
-      ->Add(value);
-}
-
-// This corresponds to UMA_HISTOGRAM_LONG_TIMES for use with dynamic histogram
-// names.
-void UmaHistogramLongTimes(const std::string& name,
-                           const base::TimeDelta& value) {
-  base::Histogram::FactoryTimeGet(
-      name, base::TimeDelta::FromMilliseconds(1), base::TimeDelta::FromHours(1),
-      50, base::HistogramBase::kUmaTargetedHistogramFlag)
-      ->AddTime(value);
-}
-
 // This corresponds to UMA_HISTOGRAM_CUSTOM_TIMES (with min/max appropriate
 // for the age of suggestions) for use with dynamic histogram names.
 void UmaHistogramAge(const std::string& name, const base::TimeDelta& value) {
@@ -165,29 +147,13 @@ void UmaHistogramAge(const std::string& name, const base::TimeDelta& value) {
       ->AddTime(value);
 }
 
-// This corresponds to UMA_HISTOGRAM_CUSTOM_COUNTS (with min/max appropriate
-// for the score of suggestions) for use with dynamic histogram names.
-void UmaHistogramScore(const std::string& name, float value) {
-  base::Histogram::FactoryGet(name, 1, 100000, 50,
-                              base::HistogramBase::kUmaTargetedHistogramFlag)
-      ->Add(value);
-}
-
-void LogCategoryHistogramEnumeration(const char* base_name,
-                                     Category category,
-                                     int value,
-                                     int boundary_value) {
-  std::string name = GetCategoryHistogramName(base_name, category);
-  // Since the histogram name is dynamic, we can't use the regular macro.
-  UmaHistogramEnumeration(name, value, boundary_value);
-}
-
-void LogCategoryHistogramLongTimes(const char* base_name,
-                                   Category category,
-                                   const base::TimeDelta& value) {
+void LogCategoryHistogramPosition(const char* base_name,
+                                  Category category,
+                                  int position,
+                                  int max_position) {
   std::string name = GetCategoryHistogramName(base_name, category);
   // Since the histogram name is dynamic, we can't use the regular macro.
-  UmaHistogramLongTimes(name, value);
+  base::UmaHistogramExactLinear(name, position, max_position);
 }
 
 void LogCategoryHistogramAge(const char* base_name,
@@ -202,8 +168,12 @@ 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);
+  // Scores are typically reported in a range of (0,1]. As UMA does not support
+  // floats, we put them on a discrete scale of [1,10]. We keep the extra bucket
+  // 11 for unexpected over-flows as we want to distinguish them from scores
+  // close to 1. For instance, the discrete value 1 represents score values
+  // within (0.0, 0.1].
+  base::UmaHistogramExactLinear(name, ceil(score * 10), 11);
 }
 
 // Records ContentSuggestions usage. Therefore the day is sliced into 20min
@@ -222,10 +192,9 @@ void RecordContentSuggestionsUsage() {
   std::string histogram_name(
       base::StringPrintf("%s.%s", kHistogramArticlesUsageTimeLocal,
                          kWeekdayNames[now_exploded.day_of_week]));
-  UmaHistogramEnumeration(histogram_name, bucket, kNumBuckets);
-
-  UMA_HISTOGRAM_ENUMERATION(kHistogramArticlesUsageTimeLocal, bucket,
-                            kNumBuckets);
+  base::UmaHistogramExactLinear(histogram_name, bucket, kNumBuckets);
+  UMA_HISTOGRAM_EXACT_LINEAR(kHistogramArticlesUsageTimeLocal, bucket,
+                             kNumBuckets);
 
   base::RecordAction(
       base::UserMetricsAction("NewTabPage_ContentSuggestions_ArticlesUsage"));
@@ -237,13 +206,12 @@ 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);
+    LogCategoryHistogramPosition(kHistogramCountOnNtpOpened, item.first,
+                                 item.second, kMaxSuggestionsPerCategory);
     suggestions_total += item.second;
   }
-
-  UMA_HISTOGRAM_ENUMERATION(kHistogramCountOnNtpOpened, suggestions_total,
-                            kMaxSuggestionsTotal);
+  UMA_HISTOGRAM_EXACT_LINEAR(kHistogramCountOnNtpOpened, suggestions_total,
+                             kMaxSuggestionsTotal);
 }
 
 void OnSuggestionShown(int global_position,
@@ -252,10 +220,10 @@ void OnSuggestionShown(int global_position,
                        base::Time publish_date,
                        base::Time last_background_fetch_time,
                        float score) {
-  UMA_HISTOGRAM_ENUMERATION(kHistogramShown, global_position,
-                            kMaxSuggestionsTotal);
-  LogCategoryHistogramEnumeration(kHistogramShown, category, category_position,
-                                  kMaxSuggestionsPerCategory);
+  UMA_HISTOGRAM_EXACT_LINEAR(kHistogramShown, global_position,
+                             kMaxSuggestionsTotal);
+  LogCategoryHistogramPosition(kHistogramShown, category, category_position,
+                               kMaxSuggestionsPerCategory);
 
   base::TimeDelta age = base::Time::Now() - publish_date;
   LogCategoryHistogramAge(kHistogramShownAge, category, age);
@@ -286,21 +254,24 @@ void OnSuggestionOpened(int global_position,
                         base::Time publish_date,
                         float score,
                         WindowOpenDisposition disposition) {
-  UMA_HISTOGRAM_ENUMERATION(kHistogramOpened, global_position,
-                            kMaxSuggestionsTotal);
-  LogCategoryHistogramEnumeration(kHistogramOpened, category, category_position,
-                                  kMaxSuggestionsPerCategory);
+  UMA_HISTOGRAM_EXACT_LINEAR(kHistogramOpened, global_position,
+                             kMaxSuggestionsTotal);
+  LogCategoryHistogramPosition(kHistogramOpened, category, category_position,
+                               kMaxSuggestionsPerCategory);
 
   base::TimeDelta age = base::Time::Now() - publish_date;
   LogCategoryHistogramAge(kHistogramOpenedAge, category, age);
 
   LogCategoryHistogramScore(kHistogramOpenedScore, category, score);
 
-  UMA_HISTOGRAM_ENUMERATION(
+  // We use WindowOpenDisposition::MAX_VALUE + 1 for |value_max| since MAX_VALUE
+  // itself is a valid (and used) enum value.
+  UMA_HISTOGRAM_EXACT_LINEAR(
       kHistogramOpenDisposition, static_cast<int>(disposition),
       static_cast<int>(WindowOpenDisposition::MAX_VALUE) + 1);
-  LogCategoryHistogramEnumeration(
-      kHistogramOpenDisposition, category, static_cast<int>(disposition),
+  base::UmaHistogramExactLinear(
+      GetCategoryHistogramName(kHistogramOpenDisposition, category),
+      static_cast<int>(disposition),
       static_cast<int>(WindowOpenDisposition::MAX_VALUE) + 1);
 
   if (category.IsKnownCategory(KnownCategories::ARTICLES)) {
@@ -313,11 +284,10 @@ void OnSuggestionMenuOpened(int global_position,
                             int category_position,
                             base::Time publish_date,
                             float score) {
-  UMA_HISTOGRAM_ENUMERATION(kHistogramMenuOpened, global_position,
-                            kMaxSuggestionsTotal);
-  LogCategoryHistogramEnumeration(kHistogramMenuOpened, category,
-                                  category_position,
-                                  kMaxSuggestionsPerCategory);
+  UMA_HISTOGRAM_EXACT_LINEAR(kHistogramMenuOpened, global_position,
+                             kMaxSuggestionsTotal);
+  LogCategoryHistogramPosition(kHistogramMenuOpened, category,
+                               category_position, kMaxSuggestionsPerCategory);
 
   base::TimeDelta age = base::Time::Now() - publish_date;
   LogCategoryHistogramAge(kHistogramMenuOpenedAge, category, age);
@@ -330,42 +300,42 @@ void OnSuggestionDismissed(int global_position,
                            int category_position,
                            bool visited) {
   if (visited) {
-    UMA_HISTOGRAM_ENUMERATION(kHistogramDismissedVisited, global_position,
-                              kMaxSuggestionsTotal);
-    LogCategoryHistogramEnumeration(kHistogramDismissedVisited, category,
-                                    category_position,
-                                    kMaxSuggestionsPerCategory);
+    UMA_HISTOGRAM_EXACT_LINEAR(kHistogramDismissedVisited, global_position,
+                               kMaxSuggestionsTotal);
+    LogCategoryHistogramPosition(kHistogramDismissedVisited, category,
+                                 category_position, kMaxSuggestionsPerCategory);
   } else {
-    UMA_HISTOGRAM_ENUMERATION(kHistogramDismissedUnvisited, global_position,
-                              kMaxSuggestionsTotal);
-    LogCategoryHistogramEnumeration(kHistogramDismissedUnvisited, category,
-                                    category_position,
-                                    kMaxSuggestionsPerCategory);
+    UMA_HISTOGRAM_EXACT_LINEAR(kHistogramDismissedUnvisited, global_position,
+                               kMaxSuggestionsTotal);
+    LogCategoryHistogramPosition(kHistogramDismissedUnvisited, category,
+                                 category_position, kMaxSuggestionsPerCategory);
   }
 }
 
 void OnSuggestionTargetVisited(Category category, base::TimeDelta visit_time) {
-  LogCategoryHistogramLongTimes(kHistogramVisitDuration, category, visit_time);
+  std::string name =
+      GetCategoryHistogramName(kHistogramVisitDuration, category);
+  base::UmaHistogramLongTimes(name, visit_time);
 }
 
 void OnMoreButtonShown(Category category, int position) {
   // The "more" card can appear in addition to the actual suggestions, so add
   // one extra bucket to this histogram.
-  LogCategoryHistogramEnumeration(kHistogramMoreButtonShown, category, position,
-                                  kMaxSuggestionsPerCategory + 1);
+  LogCategoryHistogramPosition(kHistogramMoreButtonShown, category, position,
+                               kMaxSuggestionsPerCategory + 1);
 }
 
 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);
+  LogCategoryHistogramPosition(kHistogramMoreButtonClicked, category, position,
+                               kMaxSuggestionsPerCategory + 1);
 }
 
 void OnCategoryDismissed(Category category) {
   UMA_HISTOGRAM_ENUMERATION(kHistogramCategoryDismissed,
-                            static_cast<int>(GetHistogramCategory(category)),
-                            static_cast<int>(HistogramCategories::COUNT));
+                            GetHistogramCategory(category),
+                            HistogramCategories::COUNT);
 }
 
 }  // namespace metrics