Adding UMA for persistent notifications.

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 9161e6773af9b6af81211a369b52ae5f7c4f2cab..2fbda3f6703f30084abd89adf6d6038bd34bf360 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -28493,6 +28493,27 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="PlatformNotificationService.PersistentNotificationDataDeleted"

[Alexei Svitkine (slow), 2015/05/26 19:21:23]

Can these be under the ServiceWorker.* prefix? Or is it not always related to
service workers? Generally, best practice is to not introduce a new top-level
prefix.

[Deepak, 2015/05/27 04:41:18]

Done.

[Peter Beverloo, 2015/05/27 12:28:48]

Sorry to disagree with Alexei here, but I would prefer to see them under the
"Notifications" top-level prefix in that case. My proposal:

Notifications.PersistentNotificationDataDeleted
Notifications.PersistentWebNotificationClickResult
PlatformNotificationStatus (the enum)

+    enum="Boolean">

[Alexei Svitkine (slow), 2015/05/26 19:21:23]

Please use a more specific enum than just Boolean - like BooleanSuccess or
BooleanDeleted. Add one if the most appropriate one doesn't exist yet.

[Deepak, 2015/05/27 04:41:18]

Done.

+  <owner>peter@chromium.org</owner>
+  <owner>deepak.m1@samsung.com</owner>
+  <summary>
+    Recorded when the data associated with a persistent Web Notification gets
+    deleted.

[Alexei Svitkine (slow), 2015/05/26 19:21:23]

Mention what the value means.

[Deepak, 2015/05/27 04:41:18]

Done.

+  </summary>
+</histogram>
+
+<histogram
+    name="PlatformNotificationService.PersistentWebNotificationClickResult"
+    enum="PlatformNotificationStatus">
+  <owner>peter@chromium.org</owner>
+  <owner>deepak.m1@samsumg.com</owner>
+  <summary>
+    Recorded when handling a click on a persistent Web Notification has
+    finished.
+  </summary>
+</histogram>
+
 <histogram name="PLT.Abandoned" enum="Abandoned">
   <obsolete>
     Deprecated as of 2014-06.
@@ -60792,6 +60813,15 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="16" label="I/O"/>
 </enum>
 
+<enum name="PlatformNotificationStatus" type="int">
+  <int value="0" label="PERSISTENT_NOTIFICATION_STATUS_SUCCESS"/>
+  <int value="1" label="PERSISTENT_NOTIFICATION_STATUS_NO_SERVICE_WORKER"/>
+  <int value="2" label="PERSISTENT_NOTIFICATION_STATUS_SERVICE_WORKER_ERROR"/>
+  <int value="3"
+      label="PERSISTENT_NOTIFICATION_STATUS_EVENT_WAITUNTIL_REJECTED"/>
+  <int value="4" label="PERSISTENT_NOTIFICATION_STATUS_DATABASE_ERROR"/>
+</enum>
+
 <enum name="PluginAvailabilityStatus" type="int">
   <int value="0" label="PLUGIN_NOT_REGISTERED"/>
   <int value="1" label="PLUGIN_AVAILABLE"/>