Removes code using mus client lib

ui/views/mus/drop_target_mus.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 UI_VIEWS_MUS_DROP_TARGET_MUS_H_
-#define UI_VIEWS_MUS_DROP_TARGET_MUS_H_
-
-#include <map>
-#include <memory>
-#include <string>
-#include <vector>
-
-#include "base/macros.h"
-#include "services/ui/public/cpp/window_drop_target.h"
-#include "ui/aura/window_observer.h"
-
-namespace aura {
-class Window;
-
-namespace client {
-class DragDropDelegate;
-}
-}
-
-namespace ui {
-class DropTargetEvent;
-class OSExchangeData;
-}
-
-namespace views {
-
-// An adapter class which takes signals from mus' WindowDropTarget, performs
-// targeting on the underlying aura::Window tree, and dispatches them to the
-// aura DragDropDelegate of the targeted aura::Window.
-class DropTargetMus : public ui::WindowDropTarget, public aura::WindowObserver {
- public:
-  explicit DropTargetMus(aura::Window* root_window);
-  ~DropTargetMus() override;
-
- private:
-  // Common functionality for the WindowDropTarget methods to translate from
-  // mus data types to Aura ones. This method takes in mus messages and
-  // performs the common tasks of keeping track of which aura window (along
-  // with enter/leave messages at that layer), doing coordinate translation,
-  // and creation of ui layer event objects that get dispatched to aura/views.
-  void Translate(uint32_t key_state,
-                 const gfx::Point& screen_location,
-                 uint32_t effect_bitmask,
-                 std::unique_ptr<ui::DropTargetEvent>* event,
-                 aura::client::DragDropDelegate** delegate);
-
-  void NotifyDragExited();
-
-  // Overridden from ui::WindowDropTarget:
-  void OnDragDropStart(
-      std::map<std::string, std::vector<uint8_t>> mime_data) override;
-  uint32_t OnDragEnter(uint32_t key_state,
-                       const gfx::Point& position,
-                       uint32_t effect_bitmask) override;
-  uint32_t OnDragOver(uint32_t key_state,
-                      const gfx::Point& position,
-                      uint32_t effect_bitmask) override;
-  void OnDragLeave() override;
-  uint32_t OnCompleteDrop(uint32_t key_state,
-                          const gfx::Point& position,
-                          uint32_t effect_bitmask) override;
-  void OnDragDropDone() override;
-
-  // Overridden from aura::WindowObserver:
-  void OnWindowDestroyed(aura::Window* window) override;
-
-  // The root window associated with this drop target.
-  aura::Window* root_window_;
-
-  // The Aura window that is currently under the cursor. We need to manually
-  // keep track of this because mus will only call our drag enter method once
-  // when the user enters the associated mus::Window. But inside mus there
-  // could be multiple aura windows, so we need to generate drag enter events
-  // for them.
-  aura::Window* target_window_;
-
-  // The entire drag data payload. We receive this during the drag enter event
-  // and cache it so we don't send this multiple times. We reset this value on
-  // leave or drop.
-  std::unique_ptr<ui::OSExchangeData> os_exchange_data_;
-
-  DISALLOW_COPY_AND_ASSIGN(DropTargetMus);
-};
-
-}  // namespace views
-
-#endif  // UI_VIEWS_MUS_DROP_TARGET_MUS_H_