Reject the permissionState promise with NotSupported Exception (2/3)

content/public/browser/push_messaging_service.h

Index: content/public/browser/push_messaging_service.h
diff --git a/content/public/browser/push_messaging_service.h b/content/public/browser/push_messaging_service.h
index e8e02ef2052b9b5c9e5735f6acb0fb3a3c6da7c0..d772f45091ad970c03731ce870e15908003bac8e 100644
--- a/content/public/browser/push_messaging_service.h
+++ b/content/public/browser/push_messaging_service.h
@@ -77,6 +77,11 @@ class CONTENT_EXPORT PushMessagingService {
       const GURL& embedding_origin,
       bool user_visible) = 0;
 
+  // Returns whether subscriptions that do not mandate user visible UI upon
+  // receiving a push message are supported. Influences permission request and
+  // permission check behaviour.
+  virtual bool SupportNonVisibleMessages() = 0;
+
   // Provide a storage mechanism to read/write an opaque
   // "notifications_shown_by_last_few_pushes" string associated with a Service
   // Worker registration. Stored data is deleted when the associated