Allow script to request durable storage permission (chrome side)

content/public/browser/permission_type.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_BROWSER_PERMISSION_TYPE_H_
 #define CONTENT_PUBLIC_BROWSER_PERMISSION_TYPE_H_
 
 namespace content {
 
 // This enum is also used for UMA purposes, so it needs to adhere to
 // the UMA guidelines.
 // Make sure you update histograms.xml if you add new permission types.
 // Never delete or reorder an entry; only add new entries
 // immediately before PermissionType::NUM
 enum class PermissionType {
   MIDI_SYSEX = 1,
   PUSH_MESSAGING = 2,
   NOTIFICATIONS = 3,
   GEOLOCATION = 4,
   PROTECTED_MEDIA_IDENTIFIER = 5,
   MIDI = 6,
+  DURABLE_STORAGE = 7,
 
   // Always keep this at the end.
   NUM,
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_PERMISSION_TYPE_H_