Adds a ServerViewObserver interface

services/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("//build/config/ui.gni")
 import("//mojo/public/mojo_application.gni")
 import("//testing/test.gni")
 
 mojo_native_application("view_manager") {
   sources = [
@@ skipping 29 matching lines @@
     "connection_manager_delegate.h",
     "default_access_policy.cc",
     "default_access_policy.h",
     "display_manager.cc",
     "display_manager.h",
     "scheduled_animation_group.cc",
     "scheduled_animation_group.h",
     "server_view.cc",
     "server_view.h",
     "server_view_delegate.h",
+    "server_view_observer.h",
     "view_coordinate_conversions.cc",
     "view_coordinate_conversions.h",
     "view_manager_service_impl.cc",
     "view_manager_service_impl.h",
     "window_manager_access_policy.cc",
     "window_manager_access_policy.h",
   ]
 
   public_deps = [
     "//mojo/services/view_manager/public/cpp",
@@ skipping 110 matching lines @@
     "//mojo/application",
     "//mojo/application:test_support",
     "//mojo/common",
     "//mojo/public/cpp/bindings",
     "//mojo/services/geometry/public/interfaces",
     "//mojo/services/view_manager/public/cpp",
     "//mojo/services/view_manager/public/interfaces",
     "//mojo/services/window_manager/public/interfaces",
   ]
 }