Remove all blimp engine code

blimp/engine/app/ui/blimp_window_parenting_client.h

-// Copyright 2016 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 BLIMP_ENGINE_APP_UI_BLIMP_WINDOW_PARENTING_CLIENT_H_
-#define BLIMP_ENGINE_APP_UI_BLIMP_WINDOW_PARENTING_CLIENT_H_
-
-#include "base/macros.h"
-#include "ui/aura/client/window_parenting_client.h"
-
-namespace blimp {
-namespace engine {
-
-class BlimpWindowParentingClient : public aura::client::WindowParentingClient {
- public:
-  // Caller ensures that |root_window| outlives this object.
-  explicit BlimpWindowParentingClient(aura::Window* root_window);
-
-  ~BlimpWindowParentingClient() override;
-
-  // aura::client::WindowParentingClient interface.
-  aura::Window* GetDefaultParent(aura::Window* context,
-                                 aura::Window* window,
-                                 const gfx::Rect& bounds) override;
-
- private:
-  aura::Window* root_window_;
-
-  DISALLOW_COPY_AND_ASSIGN(BlimpWindowParentingClient);
-};
-
-}  // namespace engine
-}  // namespace blimp
-
-#endif  // BLIMP_ENGINE_APP_UI_BLIMP_WINDOW_PARENTING_CLIENT_H_