[Icon cacher] Add metrics for downloading favicons for NTP Tiles

components/ntp_tiles/icon_cacher_impl.cc

Index: components/ntp_tiles/icon_cacher_impl.cc
diff --git a/components/ntp_tiles/icon_cacher_impl.cc b/components/ntp_tiles/icon_cacher_impl.cc
index 92a7d236720d009bbd790a526bc725f66df32ef5..4c900c52354af2b7114a8449a935d9ce3a38125b 100644
--- a/components/ntp_tiles/icon_cacher_impl.cc
+++ b/components/ntp_tiles/icon_cacher_impl.cc
@@ -7,6 +7,7 @@
 #include <utility>
 
 #include "base/memory/ptr_util.h"
+#include "base/metrics/histogram_macros.h"
 #include "components/favicon/core/favicon_service.h"
 #include "components/favicon/core/favicon_util.h"
 #include "components/favicon/core/large_icon_service.h"
@@ -135,6 +136,7 @@ void IconCacherImpl::OnPopularSitesFaviconDownloaded(
     const image_fetcher::RequestMetadata& metadata) {
   if (fetched_image.IsEmpty()) {
     FinishRequestAndNotifyIconAvailable(site.url, /*newly_available=*/false);
+    UMA_HISTOGRAM_BOOLEAN("NewTabPage.TileFaviconFetchSuccess.Popular", false);
     return;
   }
 
@@ -145,6 +147,7 @@ void IconCacherImpl::OnPopularSitesFaviconDownloaded(
   }
   SaveIconForSite(site, fetched_image);
   FinishRequestAndNotifyIconAvailable(site.url, /*newly_available=*/true);
+  UMA_HISTOGRAM_BOOLEAN("NewTabPage.TileFaviconFetchSuccess.Popular", true);
 }
 
 void IconCacherImpl::SaveAndNotifyDefaultIconForSite(
@@ -216,10 +219,16 @@ void IconCacherImpl::OnGetLargeIconOrFallbackStyleFinished(
   large_icon_service_
       ->GetLargeIconOrFallbackStyleFromGoogleServerSkippingLocalCache(
           page_url, kTileIconMinSizePx, kTileIconDesiredSizePx,
-          base::Bind(&IconCacherImpl::FinishRequestAndNotifyIconAvailable,
+          base::Bind(&IconCacherImpl::OnMostLikelyFaviconDownloaded,
                      weak_ptr_factory_.GetWeakPtr(), page_url));
 }
 
+void IconCacherImpl::OnMostLikelyFaviconDownloaded(const GURL& request_url,
+                                                   bool success) {
+  UMA_HISTOGRAM_BOOLEAN("NewTabPage.TileFaviconFetchSuccess.Server", success);
+  FinishRequestAndNotifyIconAvailable(request_url, success);
+}
+
 bool IconCacherImpl::StartRequest(const GURL& request_url,
                                   const base::Closure& icon_available) {
   bool in_flight = in_flight_requests_.count(request_url) > 0;