Add use counters for persistent notification interaction.

tools/metrics/actions/actions.xml

Index: tools/metrics/actions/actions.xml
diff --git a/tools/metrics/actions/actions.xml b/tools/metrics/actions/actions.xml
index 4fb51c97b85e6ef6e63143b2ea490ff77aea952e..39096aa718d22e90d41aaca5e01444d6dad477d5 100644
--- a/tools/metrics/actions/actions.xml
+++ b/tools/metrics/actions/actions.xml
@@ -8582,6 +8582,27 @@ should be able to be added at any place in this file.
   </description>
 </action>
 
+<action name="Notifications.Persistent.Clicked">
+  <owner>peter@chromium.org</owner>
+  <description>
+    Recorded when a persistent notification gets clicked on by the user.
+  </description>
+</action>
+
+<action name="Notifications.Persistent.Closed">
+  <owner>peter@chromium.org</owner>
+  <description>
+    Recorded when a persistent notification gets closed by the user. Note that
+    this is not mutually exclusive with clicked notifications if the website
+    does not close the notification on click.

[Ilya Sherman, 2015/09/01 23:02:53]

This sentence confuses me.  If a website does close the notification on click,
do both actions get recorded, or just one of them?

[Peter Beverloo, 2015/09/02 12:48:06]

This is about user-initiated responses, so then only one would be recorded. I
have clarified the message.

+  </description>
+</action>
+
+<action name="Notifications.Persistent.Shown">
+  <owner>peter@chromium.org</owner>
+  <description>Recorded when a persistent notification gets shown.</description>
+</action>
+
 <action name="Notifications.ShowMessageCenter">
   <owner>dewittj@chromium.org</owner>
   <description>