Nukes the windowmanager interface

components/view_manager/public/interfaces/BUILD.gn

 # 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.
 
 import("//build/module_args/mojo.gni")
 import("//third_party/mojo/src/mojo/public/tools/bindings/mojom.gni")
 
 mojom("interfaces") {
   sources = [
     "animations.mojom",
     "view_manager.mojom",
     "view_manager_constants.mojom",
+    "view_manager_root.mojom",
   ]
 
   import_dirs = [ get_path_info("../../../..", "abspath") ]
 
   deps = [
     "//components/native_viewport/public/interfaces",
     "//components/surfaces/public/interfaces:surface_id",
     "//mojo/application/public/interfaces",
     "//ui/mojo/events:interfaces",
     "//ui/mojo/geometry:interfaces",
   ]
 }