Revert of 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_