mojo/services/ui/views/interfaces/view_token.mojom

// 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.

[DartPackage="mojo_services"]
module mojo.ui;

// A view token is an opaque transferable reference to a view.
//
// The ViewManager provides each view with a unique view token when
// it is registered.  The token can subsequently be passed to other
// applications and may be used to add the view as a child of some
// other view or to set it as the root of a view tree.
//
// View tokens should be kept secret and should only be shared with
// the view's intended container.
//
// TODO(jeffbrown): This implementation is a temporary placeholder until
// we extend Mojo to provide a way to create tokens which cannot be forged.
struct ViewToken {
  uint32 value;
};

// A view owner provides access to the view's token and keeps the
// view alive.  When the view owner is closed, the view will be
// unregistered from the view manager.
//
// This interface is only intended to be implemented by the view manager
// to obtain the desired ownership semantics.
interface ViewOwner {
  // Gets the |ViewToken| associated with the view.
  GetToken() => (ViewToken token);
};