Add DownloadStatus metric to FaviconHandler

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index c867b90c99b1397d92be28ec3d1e64489fa3d7b9..8a98b43312771d53a56054410e68a3efcf4088eb 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -20477,6 +20477,22 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Favicons.DownloadAttempts">
+  <owner>fhorschig@chromium.org</owner>
+  <summary>
+    Records the number of icon requested until the best-fitting candidate was
+    found or there were no candidates left to check.
+  </summary>
+</histogram>
+
+<histogram name="Favicons.DownloadOutcome" enum="FaviconDownloadStatus">
+  <owner>fhorschig@chromium.org</owner>
+  <summary>
+    Records whether a download succeeded, failed or was skipped because it has
+    failed previously.
+  </summary>
+</histogram>
+
 <histogram name="Favicons.LargeIconService.DownloadedSize" units="pixels">
   <owner>jkrcal@chromium.org</owner>
   <summary>
@@ -93336,6 +93352,17 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </int>
 </enum>
 
+<enum name="FaviconDownloadStatus" type="int">
+  <int value="0" label="SUCCEEDED">Download succeeded.</int>
+  <int value="1" label="FAILED">Download failed.</int>
+  <int value="2" label="SKIPPED">
+    Download skipped because the URL was known to have failed previously.
+  </int>
+  <int value="3" label="DOWNLOAD_OUTCOME_COUNT">
+    The amount of outcomes that can a download may have.
+  </int>
+</enum>
+
 <enum name="FeatureObserver" type="int">
 <!-- Generated from third_party/WebKit/Source/core/frame/UseCounter.h -->
 
@@ -119051,6 +119078,13 @@ from previous Chrome versions.
   <affected-histogram name="Extensions.ExternalExtensionEvent"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="FaviconIconType" separator=".">
+  <suffix name="Favicons" label="Metrics for regular favicons."/>
+  <suffix name="LargeIcons" label="Metrics for large non-touch icons."/>
+  <suffix name="TouchIcons" label="Metrics for large touch icons."/>
+  <affected-histogram name="Favicons.DownloadAttempts"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="FieldPredictionSubmissionEvents" separator=".">
   <suffix name="NoSubmission" label="No observed submission."/>
   <suffix name="BasedOnAutocomplete"