Add DownloadStatus metric to FaviconHandler

components/favicon/core/favicon_handler.h

Index: components/favicon/core/favicon_handler.h
diff --git a/components/favicon/core/favicon_handler.h b/components/favicon/core/favicon_handler.h
index 9e6e22b9f97126bc1762aa49db194d4225a8f635..7451e52758f01d3148fd025814fb8c0bb28f86ac 100644
--- a/components/favicon/core/favicon_handler.h
+++ b/components/favicon/core/favicon_handler.h
@@ -75,6 +75,13 @@ class FaviconService;
 
 class FaviconHandler {
  public:
+  // Outcome of a single favicon download.

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

Nit: Remove "single". I think that the word in unnecessary

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

Gone.

+  // Recorded as Favicons.DownloadOutcome and public for testing.
+  //
+  // These values must stay in sync with the FaviconDownloadStatus enum
+  // in histograms.xml.
+  enum DownloadOutcome { SUCCEEDED = 0, FAILED = 1, SKIPPED = 2 };
+
   class Delegate {
    public:
     // Mimics WebContents::ImageDownloadCallback.