Adds a porting layer so aura can be made to work with mus

ui/aura/window_tree_host.cc

 // Copyright (c) 2013 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 "ui/aura/window_tree_host.h"
 
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/trace_event/trace_event.h"
 #include "ui/aura/client/capture_client.h"
 #include "ui/aura/client/cursor_client.h"
 #include "ui/aura/env.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_event_dispatcher.h"
+#include "ui/aura/window_port.h"
 #include "ui/aura/window_targeter.h"
 #include "ui/aura/window_tree_host_observer.h"
 #include "ui/base/ime/input_method.h"
 #include "ui/base/ime/input_method_factory.h"
 #include "ui/base/view_prop.h"
 #include "ui/compositor/dip_util.h"
 #include "ui/compositor/layer.h"
 #include "ui/display/display.h"
 #include "ui/display/screen.h"
 #include "ui/gfx/geometry/insets.h"
@@ skipping 187 matching lines @@
 
 void WindowTreeHost::Hide() {
   HideImpl();
   if (compositor())
     compositor()->SetVisible(false);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // WindowTreeHost, protected:
 
-WindowTreeHost::WindowTreeHost()
-    : window_(new Window(nullptr)),
+WindowTreeHost::WindowTreeHost() : WindowTreeHost(nullptr) {}
+
+WindowTreeHost::WindowTreeHost(std::unique_ptr<WindowPort> window_port)
+    : window_(new Window(nullptr, std::move(window_port))),
       last_cursor_(ui::kCursorNull),
       input_method_(nullptr),
-      owned_input_method_(false) {
-}
+      owned_input_method_(false) {}
 
 void WindowTreeHost::DestroyCompositor() {
   compositor_.reset();
 }
 
 void WindowTreeHost::DestroyDispatcher() {
   delete window_;
   window_ = nullptr;
   dispatcher_.reset();
 
@@ skipping 94 matching lines @@
   client::CursorClient* cursor_client = client::GetCursorClient(window());
   if (cursor_client) {
     const display::Display& display =
         display::Screen::GetScreen()->GetDisplayNearestWindow(window());
     cursor_client->SetDisplay(display);
   }
   dispatcher()->OnCursorMovedToRootLocation(root_location);
 }
 
 }  // namespace aura