Use NTPTileSource in MVS interface.

components/ntp_tiles/most_visited_sites.cc

Index: components/ntp_tiles/most_visited_sites.cc
diff --git a/components/ntp_tiles/most_visited_sites.cc b/components/ntp_tiles/most_visited_sites.cc
index 01d16418eb0e01a40fc889e79d39cd713ad43c00..0a2b0fec40e0c473372882c054a05d3498b9e2cf 100644
--- a/components/ntp_tiles/most_visited_sites.cc
+++ b/components/ntp_tiles/most_visited_sites.cc
@@ -123,15 +123,15 @@ bool AreURLsEquivalent(const GURL& url1, const GURL& url2) {
   return url1.host() == url2.host() && url1.path() == url2.path();
 }
 
-std::string GetSourceHistogramName(int source) {
+std::string GetSourceHistogramName(NTPTileSource source) {
   switch (source) {
-    case static_cast<int>(NTPTileSource::TOP_SITES):
+    case NTPTileSource::TOP_SITES:
       return kHistogramClientName;
-    case static_cast<int>(NTPTileSource::POPULAR):
+    case NTPTileSource::POPULAR:
       return kHistogramPopularName;
-    case static_cast<int>(NTPTileSource::WHITELIST):
+    case NTPTileSource::WHITELIST:
       return kHistogramWhitelistName;
-    case static_cast<int>(NTPTileSource::SUGGESTIONS_SERVICE):
+    case NTPTileSource::SUGGESTIONS_SERVICE:
       return kHistogramServerName;
   }
   NOTREACHED();
@@ -227,7 +227,7 @@ void MostVisitedSites::AddOrRemoveBlacklistedUrl(const GURL& url,
 
 void MostVisitedSites::RecordTileTypeMetrics(
     const std::vector<int>& tile_types,
-    const std::vector<int>& sources) {
+    const std::vector<NTPTileSource>& sources) {
   int counts_per_type[NUM_TILE_TYPES] = {0};
   for (size_t i = 0; i < tile_types.size(); ++i) {
     int tile_type = tile_types[i];
@@ -251,7 +251,7 @@ void MostVisitedSites::RecordTileTypeMetrics(
 
 void MostVisitedSites::RecordOpenedMostVisitedItem(int index,
                                                    int tile_type,
-                                                   int source) {
+                                                   NTPTileSource source) {
   UMA_HISTOGRAM_ENUMERATION("NewTabPage.MostVisited", index, num_sites_);
 
   std::string histogram = base::StringPrintf(
@@ -534,8 +534,7 @@ void MostVisitedSites::RecordImpressionUMAMetrics() {
 
     std::string histogram = base::StringPrintf(
         "NewTabPage.SuggestionsImpression.%s",
-        GetSourceHistogramName(static_cast<int>(current_tiles_[i].source))
-            .c_str());
+        GetSourceHistogramName(current_tiles_[i].source).c_str());
     LogHistogramEvent(histogram, static_cast<int>(i), num_sites_);
   }
 }