Changes OnWindowHierarchyChanged() to include transient parent

services/ui/public/interfaces/window_tree_constants.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.
 
 module ui.mojom;
 
 import "ui/gfx/geometry/mojo/geometry.mojom";
 
 // Contains state of a single window.
 struct WindowData {
   // Unique identifier of the parent. If the client can not see the parent an
   // id of 0 is supplied.
   uint32 parent_id;
 
   // Unique identifier of the window.
   uint32 window_id;
 
+  // Id of the transient parent, 0 if there isn't one.
+  uint32 transient_parent_id;
+
   gfx.mojom.Rect bounds;
 
   // Arbitrary key/value pairs. The interpretation of these is left to the
   // client. See SetWindowProperty() for more information.
   map<string, array<uint8>> properties;
 
   // True if this window is visible. The window may not be drawn on screen (see
   // OnWindowParentDrawnStateChanged() for details).
   bool visible;
 };
@@ skipping 28 matching lines @@
 const uint32 kDropEffectLink = 4;
 
 // When this flag is set in a call to Embed(), the embedder (i.e. the client
 // that is making the call to Embed()) will receive events that are targeted to
 // the embedded client. The embedded client will not receive any input events
 // from the window server. However, the embedder can choose to dispatch events
 // to the embedded client through other mechanism.
 // TODO(sad): Provide an API in mus for the embedder to dispatch events to the
 // embedded client. https://crbug.com/621085
 const uint32 kEmbedFlagEmbedderInterceptsEvents = 0x01;