aura-mus: add a drag representation image.

ui/aura/mus/window_manager_delegate.h

 // Copyright 2015 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_AURA_MUS_WINDOW_MANAGER_DELEGATE_H_
 #define UI_AURA_MUS_WINDOW_MANAGER_DELEGATE_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 99 matching lines @@
   virtual Window* OnWmCreateTopLevelWindow(
       ui::mojom::WindowType window_type,
       std::map<std::string, std::vector<uint8_t>>* properties) = 0;
 
   // Called when a Mus client's jankiness changes. |windows| is the set of
   // windows owned by the window manager in which the client is embedded.
   virtual void OnWmClientJankinessChanged(
       const std::set<Window*>& client_windows,
       bool janky) = 0;
 
+  // Called when a Mus client has started a drag, and wants this image to be
+  // the drag representation.
+  virtual void OnWmBuildDragImage(const gfx::Point& cursor_location,
+                                  const SkBitmap& drag_image,
+                                  const gfx::Vector2d& drag_image_offset,
+                                  ui::mojom::DragEventSource source) = 0;
+
+  // Called during drags when the drag location has changed and the drag
+  // representation must be moved.
+  virtual void OnWmMoveDragImage(const gfx::Point& cursor_location) = 0;
+
+  // Called when a drag is complete or canceled, and signals that the drag image
+  // should be removed.
+  virtual void OnWmDestroyDragImage() = 0;
+
   // When a new display is added OnWmWillCreateDisplay() is called, and then
   // OnWmNewDisplay(). OnWmWillCreateDisplay() is intended to add the display
   // to the set of displays (see Screen).
   virtual void OnWmWillCreateDisplay(const display::Display& display) = 0;
 
   // Called when a WindowTreeHostMus is created for a new display
   // Called when a display is added. |window_tree_host| is the WindowTreeHost
   // for the new display.
   virtual void OnWmNewDisplay(
       std::unique_ptr<WindowTreeHostMus> window_tree_host,
@@ skipping 38 matching lines @@
   // window.
   virtual void OnWmDeactivateWindow(Window* window) = 0;
 
  protected:
   virtual ~WindowManagerDelegate() {}
 };
 
 }  // namespace ui
 
 #endif  // UI_AURA_MUS_WINDOW_MANAGER_DELEGATE_H_