Add new method to differentiate custom notifications

Bug: b/276963581
Test: manual test with Notify1.apk
Change-Id: Ie70210abe4b7febf5ede96bca16de728f0cec70a

core/java/android/app/Notification.java

@@ -6985,6 +6985,22 @@ public class Notification implements Parcelable
         return isMediaStyle && hasMediaSession;
     }
 
+    /**
+     * @return true for custom notifications, including notifications
+     * with DecoratedCustomViewStyle or DecoratedMediaCustomViewStyle,
+     * and other notifications with user-provided custom views.
+     *
+     * @hide
+     */
+    public Boolean isCustomNotification() {
+        if (contentView == null
+                && bigContentView == null
+                && headsUpContentView == null) {
+            return false;
+        }
+        return true;
+    }
+
     /**
      * @return true if this notification is showing as a bubble
      *