Make all icon fields & extras sent to listeners backward-compatible.

This also had to be done for when retrieving existing notifications.
For final release, we will only be doing this for
notification listeners targeting older SDKs.

Bug: 21207612
Change-Id: I351f9e13cd052410e7355c956c750c3859f972cb

core/java/android/service/notification/NotificationListenerService.java

@@ -468,6 +468,8 @@ public abstract class NotificationListenerService extends Service {
             for (int i = 0; i < N; i++) {
                 Notification notification = list.get(i).getNotification();
                 Builder.rebuild(getContext(), notification);
+                // convert icon metadata to legacy format for older clients
+                createLegacyIconExtras(notification);
             }
             return list.toArray(new StatusBarNotification[N]);
         } catch (android.os.RemoteException ex) {