Add metrics for DelayNavigationThrottle

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 cd3b6aa443b104aa05784f81d3a4678e95b541f8..df455d9e0ff2cd900837c8fccffd63b4c7e3c1fb 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -10951,6 +10951,29 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="DelayNavigationThrottle.Delay.Actual" units="ms">
+  <owner>bmcquade@chromium.org</owner>
+  <summary>
+    The actual delay added to main frame navigations by DelayNavigationThrottle.
+  </summary>
+</histogram>
+
+<histogram name="DelayNavigationThrottle.Delay.Delta" units="ms">
+  <owner>bmcquade@chromium.org</owner>
+  <summary>
+    The absolute delta between the specified and actual delays added to main
+    frame navigations by DelayNavigationThrottle.
+  </summary>
+</histogram>
+
+<histogram name="DelayNavigationThrottle.Delay.Specified" units="ms">
+  <owner>bmcquade@chromium.org</owner>
+  <summary>
+    The specified delay added to main frame navigations by
+    DelayNavigationThrottle.
+  </summary>
+</histogram>
+
 <histogram name="DesktopIOSPromotion.DismissalReason"
     enum="DesktopIOSPromotionDismissalReason">
   <owner>mrefaat@chromium.org</owner>