[Android NTP] Logging histograms for users that are part of a control group.

chrome/browser/android/most_visited_sites.cc

 // Copyright 2013 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 "chrome/browser/android/most_visited_sites.h"
 
 #include <string>
 #include <vector>
 
 #include "base/android/jni_android.h"
@@ skipping 40 matching lines @@
 
 // Total number of tiles displayed.
 const char kNumTilesHistogramName[] = "NewTabPage.NumberOfTiles";
 // Tracking thumbnails.
 const char kNumLocalThumbnailTilesHistogramName[] =
     "NewTabPage.NumberOfThumbnailTiles";
 const char kNumEmptyTilesHistogramName[] = "NewTabPage.NumberOfGrayTiles";
 const char kNumServerTilesHistogramName[] = "NewTabPage.NumberOfExternalTiles";
 // Client suggestion opened.
 const char kOpenedItemClientHistogramName[] = "NewTabPage.MostVisited.client";
+// Control group suggestion opened.
+const char kOpenedItemControlHistogramName[] = "NewTabPage.MostVisited.client0";
 // Server suggestion opened, no provider.
 const char kOpenedItemServerHistogramName[] = "NewTabPage.MostVisited.server";
 // Server suggestion opened with provider.
 const char kOpenedItemServerProviderHistogramFormat[] =
     "NewTabPage.MostVisited.server%d";
 // Client impression.
 const char kImpressionClientHistogramName[] =
     "NewTabPage.SuggestionsImpression.client";
+// Control group impression.
+const char kImpressionControlHistogramName[] =
+    "NewTabPage.SuggestionsImpression.client0";
 // Server suggestion impression, no provider.
 const char kImpressionServerHistogramName[] =
     "NewTabPage.SuggestionsImpression.server";
 // Server suggestion impression with provider.
 const char kImpressionServerHistogramFormat[] =
     "NewTabPage.SuggestionsImpression.server%d";
 
 void ExtractMostVisitedTitlesAndURLs(
     const history::MostVisitedURLList& visited_list,
     std::vector<base::string16>* titles,
@@ skipping 82 matching lines @@
       1,
       num_sites,
       num_sites + 1,
       base::Histogram::kUmaTargetedHistogramFlag);
   counter->Add(position);
 }
 
 }  // namespace
 
 MostVisitedSites::MostVisitedSites(Profile* profile)
-    : profile_(profile), num_sites_(0), num_local_thumbs_(0),
-      num_server_thumbs_(0), num_empty_thumbs_(0), weak_ptr_factory_(this) {
+    : profile_(profile), num_sites_(0), is_control_group_(false),
+      num_local_thumbs_(0), num_server_thumbs_(0), num_empty_thumbs_(0),
+      weak_ptr_factory_(this) {
   // Register the debugging page for the Suggestions Service and the thumbnails
   // debugging page.
   content::URLDataSource::Add(profile_,
                               new suggestions::SuggestionsSource(profile_));
   content::URLDataSource::Add(profile_, new ThumbnailListSource(profile_));
 }
 
 MostVisitedSites::~MostVisitedSites() {
 }
 
@@ skipping 88 matching lines @@
       break;
     }
   }
 }
 
 void MostVisitedSites::RecordOpenedMostVisitedItem(JNIEnv* env,
                                                    jobject obj,
                                                    jint index) {
   switch (mv_source_) {
     case TOP_SITES: {
-      HISTOGRAM_SPARSE_SLOWLY(kOpenedItemClientHistogramName, index);
+      UMA_HISTOGRAM_SPARSE_SLOWLY(is_control_group_ ?
+          kOpenedItemControlHistogramName : kOpenedItemClientHistogramName,
+          index);

[beaudoin1, 2014/06/18 17:46:54]

I know many histogram macros do not support a dynamic histogram name. From a
cursory look it seems that this specific one may be good, but you may want to
double check.

If is_control_group_ ever changes and the macro doesn't support dynamic names I
believe it will trigger a DCHECK. This would make for a very strange behaviour.
From looking at the code, I don't think there is a strong guarantee that
is_control_group_ will never change.

[Mathieu, 2014/06/18 17:55:09]

Ah good catch, I even have the function in this file to log dynamic histograms.
Changed.

       break;
     }
     case SUGGESTIONS_SERVICE: {
       if (server_suggestions_.suggestions_size() > index) {
         if (server_suggestions_.suggestions(index).providers_size()) {
           std::string histogram = base::StringPrintf(
               kOpenedItemServerProviderHistogramFormat,
               server_suggestions_.suggestions(index).providers(0));
           LogHistogramEvent(histogram, index, num_sites_);
         } else {
-          HISTOGRAM_SPARSE_SLOWLY(kOpenedItemServerHistogramName, index);
+          UMA_HISTOGRAM_SPARSE_SLOWLY(kOpenedItemServerHistogramName, index);

[beaudoin1, 2014/06/18 17:46:54]

Out of curiosity: What's the difference between the regular and UMA_ flavor of
the macro?

[Mathieu, 2014/06/18 17:55:09]

The COUNTS macros don't work very well when the maximum is dynamic. It should be
the same across all callers of the macro. So on desktop the max is 8 but here it
varies. SPARSE works best. 

         }
       }
       break;
     }
   }
 }
 
 void MostVisitedSites::Observe(int type,
                                const content::NotificationSource& source,
                                const content::NotificationDetails& details) {
@@ skipping 43 matching lines @@
     ScopedJavaGlobalRef<jobject>* j_observer,
     int num_sites,
     const history::MostVisitedURLList& visited_list) {
   std::vector<base::string16> titles;
   std::vector<std::string> urls;
   ExtractMostVisitedTitlesAndURLs(visited_list, &titles, &urls, num_sites);
 
   mv_source_ = TOP_SITES;
 
   int num_tiles = urls.size();
-  HISTOGRAM_SPARSE_SLOWLY(kNumTilesHistogramName, num_tiles);
+  UMA_HISTOGRAM_SPARSE_SLOWLY(kNumTilesHistogramName, num_tiles);
   for (int i = 0; i < num_tiles; ++i) {
-    HISTOGRAM_SPARSE_SLOWLY(kImpressionClientHistogramName, i);
+    UMA_HISTOGRAM_SPARSE_SLOWLY(is_control_group_ ?
+        kImpressionControlHistogramName : kImpressionClientHistogramName, i);

[beaudoin1, 2014/06/18 17:46:54]

Same remark here.

[Mathieu, 2014/06/18 17:55:09]

Done.

   }
 
   JNIEnv* env = AttachCurrentThread();
   Java_MostVisitedURLsObserver_onMostVisitedURLsAvailable(
       env,
       j_observer->obj(),
       ToJavaArrayOfStrings(env, titles).obj(),
       ToJavaArrayOfStrings(env, urls).obj());
 }
 
 void MostVisitedSites::OnSuggestionsProfileAvailable(
     ScopedJavaGlobalRef<jobject>* j_observer,
     const SuggestionsProfile& suggestions_profile) {
   int size = suggestions_profile.suggestions_size();
-  if (size == 0) {
-    // No suggestions data available, initiate Top Sites query.
+
+  // Determine if the user is in a control group (they would have received
+  // suggestions, but are in a group where they shouldn't).
+  is_control_group_ = size && SuggestionsService::IsControlGroup();
+
+  // If no suggestions data is available or the user is in a control group,
+  // initiate Top Sites query.
+  if (is_control_group_ || !size) {
     InitiateTopSitesQuery();
     return;
   }
 
   std::vector<base::string16> titles;
   std::vector<std::string> urls;
 
   int i = 0;
   for (; i < size && i < num_sites_; ++i) {
     const ChromeSuggestion& suggestion = suggestions_profile.suggestions(i);
     titles.push_back(base::UTF8ToUTF16(suggestion.title()));
     urls.push_back(suggestion.url());
     if (suggestion.providers_size()) {
       std::string histogram = base::StringPrintf(
           kImpressionServerHistogramFormat, suggestion.providers(0));
       LogHistogramEvent(histogram, i, num_sites_);
     } else {
-      HISTOGRAM_SPARSE_SLOWLY(kImpressionServerHistogramName, i);
+      UMA_HISTOGRAM_SPARSE_SLOWLY(kImpressionServerHistogramName, i);
     }
   }
-  HISTOGRAM_SPARSE_SLOWLY(kNumTilesHistogramName, i);
+  UMA_HISTOGRAM_SPARSE_SLOWLY(kNumTilesHistogramName, i);
 
   mv_source_ = SUGGESTIONS_SERVICE;
   // Keep a copy of the suggestions for eventual logging.
   server_suggestions_ = suggestions_profile;
 
   JNIEnv* env = AttachCurrentThread();
   Java_MostVisitedURLsObserver_onMostVisitedURLsAvailable(
       env,
       j_observer->obj(),
       ToJavaArrayOfStrings(env, titles).obj(),
@@ skipping 41 matching lines @@
         gfx::ConvertToJavaBitmap(bitmap).obj());
   } else {
     num_empty_thumbs_++;
   }
 
   Java_ThumbnailCallback_onMostVisitedURLsThumbnailAvailable(
       env, j_callback->obj(), j_bitmap_ref->obj());
 }
 
 void MostVisitedSites::RecordUMAMetrics() {
-  HISTOGRAM_SPARSE_SLOWLY(kNumLocalThumbnailTilesHistogramName,
+  UMA_HISTOGRAM_SPARSE_SLOWLY(kNumLocalThumbnailTilesHistogramName,
                           num_local_thumbs_);
   num_local_thumbs_ = 0;
-  HISTOGRAM_SPARSE_SLOWLY(kNumEmptyTilesHistogramName, num_empty_thumbs_);
+  UMA_HISTOGRAM_SPARSE_SLOWLY(kNumEmptyTilesHistogramName, num_empty_thumbs_);
   num_empty_thumbs_ = 0;
-  HISTOGRAM_SPARSE_SLOWLY(kNumServerTilesHistogramName, num_server_thumbs_);
+  UMA_HISTOGRAM_SPARSE_SLOWLY(kNumServerTilesHistogramName, num_server_thumbs_);
   num_server_thumbs_ = 0;
 }
 
 static jlong Init(JNIEnv* env, jobject obj, jobject jprofile) {
   MostVisitedSites* most_visited_sites =
       new MostVisitedSites(ProfileAndroid::FromProfileAndroid(jprofile));
   return reinterpret_cast<intptr_t>(most_visited_sites);
 }