Desktop NTP: Add a UMA metric NewTabPage.TilesReceivedTime

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 f633c570314e4a3226644468ffd9143dc3f490e3..4a26487f0b7f8c8126a8cbf9eb45ca13e186b77c 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -40781,6 +40781,16 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="NewTabPage.TilesReceivedTime" units="ms">
+  <owner>treib@chromium.org</owner>
+  <summary>
+    Histogram of the time, in milliseconds since navigation start, it took for
+    the NTP most visited iframe to receive the data for all of its tiles. This
+    does not include actually loading the DOM elements for the tiles, in
+    particular the thumbnail images; see NewTabPage.LoadTime for that.
+  </summary>
+</histogram>
+
 <histogram name="NewTabPage.TileType" enum="MostVisitedTileType">
   <owner>newt@chromium.org</owner>
   <summary>
@@ -116563,6 +116573,7 @@ value.
   <suffix name="Startup" label="NTP loaded during browser startup."/>
   <suffix name="NewTab" label="NTP loaded on a new tab."/>
   <affected-histogram name="NewTabPage.LoadTime"/>
+  <affected-histogram name="NewTabPage.TilesReceivedTime"/>
 </histogram_suffixes>
 
 <histogram_suffixes name="NextTabState">