PaymentHandler: Implement requestPermission().

third_party/WebKit/public/platform/modules/permissions/permission.mojom

 // 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.
 
 module blink.mojom;
 
 import "third_party/WebKit/public/platform/modules/permissions/permission_status.mojom";
 import "url/mojo/origin.mojom";
 
 enum PermissionName {
   GEOLOCATION,
   NOTIFICATIONS,
   PUSH_NOTIFICATIONS,
   MIDI,
   PROTECTED_MEDIA_IDENTIFIER,
   DURABLE_STORAGE,
   AUDIO_CAPTURE,
   VIDEO_CAPTURE,
   BACKGROUND_SYNC,
+  PAYMENT_HANDLER,
 };
 
 struct MidiPermissionDescriptor {
   bool sysex;
 };
 
 // Union of possible extensions to the base PermissionDescriptor type.
 union PermissionDescriptorExtension {
   MidiPermissionDescriptor midi;
 };
@@ skipping 24 matching lines @@
     => (array<PermissionStatus> statuses);
   RevokePermission(PermissionDescriptor permission, url.mojom.Origin origin)
     => (PermissionStatus status);
   // Subscribes |observer| to updates about changes to |origin|'s access to
   // |permission|. Closing the pipe will cancel the subscription.
   AddPermissionObserver(PermissionDescriptor permission,
                         url.mojom.Origin origin,
                         PermissionStatus last_known_status,
                         PermissionObserver observer);
 };