NTP: Fix metrics recording crash by plumbing the necessary data to Java.

components/ntp_tiles/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 "components/ntp_tiles/most_visited_sites.h"
 
 #include <algorithm>
 #include <set>
 #include <utility>
 
@@ skipping 31 matching lines @@
 const char kHistogramServerName[] = "server";
 const char kHistogramServerFormat[] = "server%d";
 const char kHistogramPopularName[] = "popular";
 const char kHistogramWhitelistName[] = "whitelist";
 
 const char kPopularSitesFieldTrialName[] = "NTPPopularSites";
 
 const base::Feature kDisplaySuggestionsServiceTiles{
     "DisplaySuggestionsServiceTiles", base::FEATURE_ENABLED_BY_DEFAULT};
 
-// The visual type of a most visited tile.
-//
-// These values must stay in sync with the MostVisitedTileType enum
-// in histograms.xml.
-//
-// A Java counterpart will be generated for this enum.
-// GENERATED_JAVA_ENUM_PACKAGE: org.chromium.chrome.browser.ntp
-enum MostVisitedTileType {
-    // The icon or thumbnail hasn't loaded yet.
-    NONE,
-    // The item displays a site's actual favicon or touch icon.
-    ICON_REAL,
-    // The item displays a color derived from the site's favicon or touch icon.
-    ICON_COLOR,
-    // The item displays a default gray box in place of an icon.
-    ICON_DEFAULT,
-    NUM_TILE_TYPES,
-};
-
 // Log an event for a given |histogram| at a given element |position|. This
 // routine exists because regular histogram macros are cached thus can't be used
 // if the name of the histogram will change at a given call site.
 void LogHistogramEvent(const std::string& histogram,
                        int position,
                        int num_sites) {
   base::HistogramBase* counter = base::LinearHistogram::FactoryGet(
       histogram,
       1,
       num_sites,
@@ skipping 45 matching lines @@
   }
   // The whole grid is already filled with personal suggestions, no point in
   // bothering with popular ones.
   return false;
 }
 
 bool AreURLsEquivalent(const GURL& url1, const GURL& url2) {
   return url1.host() == url2.host() && url1.path() == url2.path();
 }
 
-std::string GetSourceHistogramName(
-        const MostVisitedSites::Suggestion& suggestion) {
-  switch (suggestion.source) {
+std::string GetSourceHistogramName(int source, int provider_index) {
+  switch (source) {
     case MostVisitedSites::TOP_SITES:
       return kHistogramClientName;
     case MostVisitedSites::POPULAR:
       return kHistogramPopularName;
     case MostVisitedSites::WHITELIST:
       return kHistogramWhitelistName;
     case MostVisitedSites::SUGGESTIONS_SERVICE:
-      return suggestion.provider_index >= 0
-                 ? base::StringPrintf(kHistogramServerFormat,
-                                      suggestion.provider_index)
+      return provider_index >= 0
+                 ? base::StringPrintf(kHistogramServerFormat, provider_index)
                  : kHistogramServerName;
   }
   NOTREACHED();
   return std::string();
 }
 
+std::string GetSourceHistogramNameFromSuggestion(
+    const MostVisitedSites::Suggestion& suggestion) {
+  return GetSourceHistogramName(suggestion.source, suggestion.provider_index);
+}
+
 void AppendSuggestions(MostVisitedSites::SuggestionsVector src,
                        MostVisitedSites::SuggestionsVector* dst) {
   dst->insert(dst->end(),
               std::make_move_iterator(src.begin()),
               std::make_move_iterator(src.end()));
 }
 
 }  // namespace
 
 MostVisitedSites::Suggestion::Suggestion() : provider_index(-1) {}
@@ skipping 90 matching lines @@
   // Only blacklist in the server-side suggestions service if it's active.
   if (mv_source_ == SUGGESTIONS_SERVICE) {
     if (add_url)
       suggestions_service_->BlacklistURL(url);
     else
       suggestions_service_->UndoBlacklistURL(url);
   }
 }
 
 void MostVisitedSites::RecordTileTypeMetrics(
-    const std::vector<int>& tile_types) {
-  DCHECK_EQ(current_suggestions_.size(), tile_types.size());
+    const std::vector<int>& tile_types,
+    const std::vector<int>& sources,
+    const std::vector<int>& provider_indices) {
   int counts_per_type[NUM_TILE_TYPES] = {0};
   for (size_t i = 0; i < tile_types.size(); ++i) {
     int tile_type = tile_types[i];
     ++counts_per_type[tile_type];
     std::string histogram = base::StringPrintf(
         "NewTabPage.TileType.%s",
-        GetSourceHistogramName(current_suggestions_[i]).c_str());
+        GetSourceHistogramName(sources[i], provider_indices[i]).c_str());
     LogHistogramEvent(histogram, tile_type, NUM_TILE_TYPES);
   }
 
   UMA_HISTOGRAM_SPARSE_SLOWLY("NewTabPage.IconsReal",
                               counts_per_type[ICON_REAL]);
   UMA_HISTOGRAM_SPARSE_SLOWLY("NewTabPage.IconsColor",
                               counts_per_type[ICON_COLOR]);
   UMA_HISTOGRAM_SPARSE_SLOWLY("NewTabPage.IconsGray",
                               counts_per_type[ICON_DEFAULT]);
 }
 
 void MostVisitedSites::RecordOpenedMostVisitedItem(int index, int tile_type) {
   DCHECK_GE(index, 0);
   DCHECK_LT(index, static_cast<int>(current_suggestions_.size()));

[Marc Treib, 2016/07/01 10:01:04]

Huh, now that I look at this, it seems that this method has the exact same
problem - |current_suggestions_| might have changed since the UI got its copy,
right?
Clearly it's not your responsibility to fix this, but would you mind adding a
TODO(treib)?

[dewittj, 2016/07/01 21:35:21]

Done.

   std::string histogram = base::StringPrintf(
       "NewTabPage.MostVisited.%s",
-      GetSourceHistogramName(current_suggestions_[index]).c_str());
+      GetSourceHistogramNameFromSuggestion(current_suggestions_[index])
+          .c_str());
   LogHistogramEvent(histogram, index, num_sites_);
 
   histogram = base::StringPrintf(
       "NewTabPage.TileTypeClicked.%s",
-      GetSourceHistogramName(current_suggestions_[index]).c_str());
+      GetSourceHistogramNameFromSuggestion(current_suggestions_[index])
+          .c_str());
   LogHistogramEvent(histogram, tile_type, NUM_TILE_TYPES);
 }
 
 void MostVisitedSites::OnBlockedSitesChanged() {
   BuildCurrentSuggestions();
 }
 
 // static
 void MostVisitedSites::RegisterProfilePrefs(
     user_prefs::PrefRegistrySyncable* registry) {
@@ skipping 252 matching lines @@
   observer_->OnPopularURLsAvailable(popular_sites_->sites());
 
   // Re-build the suggestions list. Once done, this will notify the observer.
   BuildCurrentSuggestions();
 }
 
 void MostVisitedSites::RecordImpressionUMAMetrics() {
   for (size_t i = 0; i < current_suggestions_.size(); i++) {
     std::string histogram = base::StringPrintf(
         "NewTabPage.SuggestionsImpression.%s",
-        GetSourceHistogramName(current_suggestions_[i]).c_str());
+        GetSourceHistogramNameFromSuggestion(current_suggestions_[i]).c_str());
     LogHistogramEvent(histogram, static_cast<int>(i), num_sites_);
   }
 }
 
 void MostVisitedSites::TopSitesLoaded(TopSites* top_sites) {}
 
 void MostVisitedSites::TopSitesChanged(TopSites* top_sites,
                                        ChangeReason change_reason) {
   if (mv_source_ == TOP_SITES) {
     // The displayed suggestions are invalidated.
     InitiateTopSitesQuery();
   }
 }
 
 }  // namespace ntp_tiles