Remove remote tree host and some related input and metro_driver code

ash/host/ash_remote_window_tree_host_win.h

-// 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.
-
-#ifndef ASH_HOST_REMOTE_WINDOW_TREE_HOST_WIN_H_
-#define ASH_HOST_REMOTE_WINDOW_TREE_HOST_WIN_H_
-
-#include <windows.h>
-
-#include "ash/ash_export.h"
-#include "ash/host/ash_window_tree_host.h"
-#include "ash/host/transformer_helper.h"
-#include "base/macros.h"
-#include "ui/aura/remote_window_tree_host_win.h"
-
-namespace ash {
-
-class ASH_EXPORT AshRemoteWindowTreeHostWin
-    : public AshWindowTreeHost,
-      public aura::RemoteWindowTreeHostWin {
- public:
-  explicit AshRemoteWindowTreeHostWin(HWND remote_hwnd);
-
- private:
-  ~AshRemoteWindowTreeHostWin() override;
-
-  // AshWindowTreeHost:
-  void ToggleFullScreen() override;
-  bool ConfineCursorToRootWindow() override;
-  void UnConfineCursor() override;
-  void SetRootWindowTransformer(
-      scoped_ptr<RootWindowTransformer> transformer) override;
-  gfx::Insets GetHostInsets() const override;
-  aura::WindowTreeHost* AsWindowTreeHost() override;
-
-  // WindowTreeHostWin:
-  gfx::Transform GetRootTransform() const override;
-  void SetRootTransform(const gfx::Transform& transform) override;
-  gfx::Transform GetInverseRootTransform() const override;
-  void UpdateRootWindowSize(const gfx::Size& host_size) override;
-
-  // ui::internal::InputMethodDelegate:
-  ui::EventDispatchDetails DispatchKeyEventPostIME(
-      ui::KeyEvent* event) override;
-
-  TransformerHelper transformer_helper_;
-
-  DISALLOW_COPY_AND_ASSIGN(AshRemoteWindowTreeHostWin);
-};
-
-}  // namespace ash
-
-#endif  // ASH_HOST_REMOTE_WINDOW_TREE_HOST_WIN_H_