Migrate the notification permission to the new common permission classes.

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 717ca5d79b8bf96a1be5a04a2709221968515d69..cb19c583df6966f68174b71ef8bc3d9ac845abc4 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -44505,6 +44505,7 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <int value="0" label="PERMISSION_UNKONWN"/>
   <int value="1" label="PERMISSION_MIDI_SYSEX"/>
   <int value="2" label="PERMISSION_PUSH_MESSAGING"/>
+  <int value="3" label="PERMISSION_NOTIFICATIONS"/>
 </enum>
 
 <enum name="PhotoEditorFileType" type="int">
@@ -50912,6 +50913,7 @@ Therefore, the affected-histogram name has to have at least one dot in it.
 <histogram_suffixes name="PermissionActions">
   <suffix name="MidiSysEx" label="Midi SysEx permsision actions"/>
   <suffix name="PushMessaging" label="Push messaging permission actions"/>
+  <suffix name="Notifications" label="Notification permission actions"/>
   <affected-histogram name="ContentSettings.PermissionActions"/>
 </histogram_suffixes>