Push API: use an enum to indicate status.

content/public/common/push_messaging_status.h

+// Copyright 2014 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_MESSAGING_STATUS_STATUS_H_
+#define CONTENT_PUBLIC_COMMON_PUSH_MESSAGING_STATUS_STATUS_H_
+
+namespace content {
+
+enum PushMessagingStatus {
+  // Everything is ok.
+  PUSH_MESSAGING_STATUS_OK,
+
+  // Registration failed because there is no Service Worker.
+  PUSH_MESSAGING_STATUS_REGISTRATION_FAILED_NO_SERVICE_WORKER,
+
+  // Registration failed because the push service is not available.
+  PUSH_MESSAGING_STATUS_REGISTRATION_FAILED_SERVICE_NOT_AVAILABLE,
+
+  // Registration failed because the maximum number of registratons has been
+  // reached.
+  PUSH_MESSAGING_STATUS_REGISTRATION_FAILED_LIMIT_REACHED,
+
+  // Registration failed because permission was denied.
+  PUSH_MESSAGING_STATUS_REGISTRATION_FAILED_PERMISSION_DENIED,
+
+  // Registration failed in the push service implemented by the embedder.
+  PUSH_MESSAGING_STATUS_REGISTRATION_FAILED_SERVICE_ERROR,
+
+  // Generic error (a more specific error should be used whenever possible).
+  PUSH_MESSAGING_STATUS_ERROR,
+
+  // Used for IPC message range checks.
+  PUSH_MESSAGING_STATUS_LAST = PUSH_MESSAGING_STATUS_ERROR
+};
+
+const char* PushMessagingStatusToString(PushMessagingStatus status);
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_COMMON_PUSH_MESSAGING_STATUS_STATUS_H_