Implement notificationclose event

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 ac36d312131f86bd5b37b11d6c6f6ca361e3ef6e..0af52ed3ec909f6f8fea1fbffc054a5386e13950 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -31013,6 +31013,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
     enum="BooleanSuccess">
   <owner>peter@chromium.org</owner>
   <owner>deepak.m1@samsung.com</owner>
+  <obsolete>
+    Deprecated 01/2016, no longer used.
+  </obsolete>
   <summary>
     Recorded when the data associated with a persistent Web Notification gets
     deleted. The value will be true if data deletion succeeded, and false if
@@ -31030,6 +31033,16 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Notifications.PersistentWebNotificationCloseResult"
+    enum="PlatformNotificationStatus">
+  <owner>peter@chromium.org</owner>
+  <owner>nsatragno@chromium.org</owner>
+  <summary>
+    Records delivery status for persistent notification close events sent to a
+    Service Worker when the event has been handled.
+  </summary>
+</histogram>
+
 <histogram name="NQE.DifferenceRTTActualAndEstimated" units="ms">
   <owner>bengr@chromium.org</owner>
   <owner>tbansal@chromium.org</owner>
@@ -44435,6 +44448,16 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="ServiceWorker.NotificationCloseEvent.Time" units="ms">
+  <owner>nsatragno@chromium.org</owner>
+  <owner>peter@chromium.org</owner>
+  <summary>
+    The time taken between dispatching a NotificationCloseEvent to a Service
+    Worker and receiving a message that it finished handling the event. Includes
+    the time for the waitUntil() promise to settle.
+  </summary>
+</histogram>
+
 <histogram name="ServiceWorker.PageLoad" enum="ServiceWorkerSite">
   <owner>falken@chromium.org</owner>
   <summary>Counts page loads controlled by a service worker.</summary>