Update the PushEvent to have a nullable PushMessageData

content/browser/push_messaging/push_messaging_router.h

Index: content/browser/push_messaging/push_messaging_router.h
diff --git a/content/browser/push_messaging/push_messaging_router.h b/content/browser/push_messaging/push_messaging_router.h
index dae9973de2627030fd2c66440d4a3b7434b48b51..5a0f2344ac00a47dcad9b96cc0ce7084127b11db 100644
--- a/content/browser/push_messaging/push_messaging_router.h
+++ b/content/browser/push_messaging/push_messaging_router.h
@@ -17,6 +17,7 @@
 namespace content {
 
 class BrowserContext;
+struct PushEventPayload;
 class ServiceWorkerContextWrapper;
 class ServiceWorkerRegistration;
 
@@ -31,7 +32,7 @@ class PushMessagingRouter {
       BrowserContext* browser_context,
       const GURL& origin,
       int64_t service_worker_registration_id,
-      const std::string& data,
+      const PushEventPayload& payload,
       const DeliverMessageCallback& deliver_message_callback);
 
  private:
@@ -40,7 +41,7 @@ class PushMessagingRouter {
   static void FindServiceWorkerRegistration(
       const GURL& origin,
       int64_t service_worker_registration_id,
-      const std::string& data,
+      const PushEventPayload& payload,
       const DeliverMessageCallback& deliver_message_callback,
       scoped_refptr<ServiceWorkerContextWrapper> service_worker_context);
 
@@ -48,7 +49,7 @@ class PushMessagingRouter {
   // |data| on the Service Worker identified by |service_worker_registration|.
   // Must be called on the IO thread.
   static void FindServiceWorkerRegistrationCallback(
-      const std::string& data,
+      const PushEventPayload& payload,
       const DeliverMessageCallback& deliver_message_callback,
       ServiceWorkerStatusCode service_worker_status,
       const scoped_refptr<ServiceWorkerRegistration>&