Adds constants and runner for animations

mojo/services/public/interfaces/view_manager/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("//mojo/public/tools/bindings/mojom.gni")
 
 mojom("view_manager") {
   sources = [
+    "animations.mojom",
     "view_manager.mojom",
     "view_manager_constants.mojom",
   ]
 
   deps = [
     "//mojo/public/interfaces/application",
     "//mojo/services/public/interfaces/geometry",
     "//mojo/services/public/interfaces/input_events",
     "//mojo/services/public/interfaces/surfaces:surface_id",
   ]
 }