NoMan: Log canceled notifications

In addition to logging cancelation command, also log actually
canceled notifications via the new eventlog tag notification_canceled.

Bug: 18083122
Change-Id: I1e3e1e1368f39519f34c002ae374f318f647a401

services/core/java/com/android/server/EventLogTags.logtags

@@ -71,6 +71,8 @@ option java_package com.android.server
 27520 notification_clicked (key|3)
 # when a notification action button has been clicked
 27521 notification_action_clicked (key|3),(action_index|1)
+# when a notification has been canceled
+27530 notification_canceled (key|3),(reason|1)
 
 # ---------------------------
 # Watchdog.java

services/core/java/com/android/server/notification/NotificationManagerService.java

@@ -2372,6 +2372,8 @@ public class NotificationManagerService extends SystemService {
 
         // Save it for users of getHistoricalNotifications()
         mArchive.record(r.sbn);
+
+        EventLogTags.writeNotificationCanceled(r.getKey(), reason);
     }
 
     /**