Update the PushEvent to have a nullable PushMessageData

content/public/common/push_event_payload.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CONTENT_PUBLIC_COMMON_PUSH_EVENT_PAYLOAD_H_
+#define CONTENT_PUBLIC_COMMON_PUSH_EVENT_PAYLOAD_H_
+
+#include <string>
+
+#include "content/common/content_export.h"
+
+namespace content {
+
+// Structure representing the payload delivered as part of a push message.
+// This struct contains the decrypted information sent from the push
+// service as part of a PushEvent as well as metadata about the information.
+struct CONTENT_EXPORT PushEventPayload {
+  PushEventPayload() : is_null(true) {}
+  ~PushEventPayload() {}
+
+  // Method to both set the data string and update the null status.
+  void setData(const std::string& data_in) {
+    data = data_in;
+    is_null = false;
+  }
+
+  // Data contained in the payload.
+  std::string data;
+
+  // Whether the payload is null or not. Payloads can be valid with non-empty
+  // content, valid with empty content, or null.
+  bool is_null;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_COMMON_PUSH_EVENT_PAYLOAD_H_