Add DownloadStatus metric to FaviconHandler

components/favicon/core/favicon_handler.cc

Index: components/favicon/core/favicon_handler.cc
diff --git a/components/favicon/core/favicon_handler.cc b/components/favicon/core/favicon_handler.cc
index bc8aa18d611ad2ece93792415395d9d0f604f34a..eb69b6da149b2f34a9423e80ba4b97cc902a166b 100644
--- a/components/favicon/core/favicon_handler.cc
+++ b/components/favicon/core/favicon_handler.cc
@@ -375,8 +375,13 @@ void FaviconHandler::OnDidDownloadFavicon(
 
   if (bitmaps.empty() && http_status_code == 404) {
     DVLOG(1) << "Failed to Download Favicon:" << image_url;
+    UMA_HISTOGRAM_COUNTS_100("Favicons.DownloadOutcome",
+                             DownloadOutcome::FAILED);
     if (service_)
       service_->UnableToDownloadFavicon(image_url);
+  } else if (http_status_code == 200) {

[pkotwicz, 2017/04/10 18:30:59]

Can we record this whenever !bitmaps.empty()

[fhorschig, 2017/04/11 12:24:53]

Done.

+    UMA_HISTOGRAM_COUNTS_100("Favicons.DownloadOutcome",
+                             DownloadOutcome::SUCCEEDED);
   }
 
   bool request_next_icon = true;
@@ -545,6 +550,8 @@ void FaviconHandler::ScheduleDownload(const GURL& image_url,
   DCHECK(download_request_.IsCancelled()) << "More than one ongoing download";
   if (service_ && service_->WasUnableToDownloadFavicon(image_url)) {
     DVLOG(1) << "Skip Failed FavIcon: " << image_url;
+    UMA_HISTOGRAM_COUNTS_100("Favicons.DownloadOutcome",
+                             DownloadOutcome::SKIPPED);
     OnDidDownloadFavicon(icon_type, 0, 0, image_url, std::vector<SkBitmap>(),
                          std::vector<gfx::Size>());
     return;