mus: Add EventObserver to allow passively listening to UI events

mash/wm/window_manager_application.cc

 // Copyright 2015 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.
 
 #include "mash/wm/window_manager_application.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/memory/ptr_util.h"
-#include "components/mus/public/cpp/event_matcher.h"
+#include "components/mus/public/cpp/event_matcher_util.h"
 #include "components/mus/public/cpp/window.h"
 #include "components/mus/public/interfaces/window_manager_factory.mojom.h"
 #include "mash/wm/accelerator_registrar_impl.h"
 #include "mash/wm/root_window_controller.h"
 #include "mash/wm/root_windows_observer.h"
 #include "mash/wm/shelf_layout.h"
 #include "mash/wm/user_window_controller_impl.h"
 #include "mojo/converters/input_events/input_events_type_converters.h"
 #include "services/shell/public/cpp/connection.h"
 #include "services/shell/public/cpp/connector.h"
@@ skipping 163 matching lines @@
 
 void WindowManagerApplication::CreateWindowManager(
     mus::mojom::DisplayPtr display,
     mojo::InterfaceRequest<mus::mojom::WindowTreeClient> client_request) {
   root_controllers_.insert(RootWindowController::CreateFromDisplay(
       this, std::move(display), std::move(client_request)));
 }
 
 }  // namespace wm
 }  // namespace mash