aura-mus: add a drag representation image.

services/ui/demo/mus_demo_internal.cc

 // Copyright 2017 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.
 
 #include "services/ui/demo/mus_demo_internal.h"
 
 #include "services/service_manager/public/cpp/service_context.h"
 #include "services/ui/demo/window_tree_data.h"
 #include "ui/aura/mus/window_tree_client.h"
 #include "ui/aura/mus/window_tree_host_mus.h"
@@ skipping 47 matching lines @@
   NOTREACHED();
   return nullptr;
 }
 
 void MusDemoInternal::OnWmClientJankinessChanged(
     const std::set<aura::Window*>& client_windows,
     bool janky) {
   // Don't care
 }
 
+void MusDemoInternal::OnWmBuildDragImage(const gfx::Point& cursor_location,
+                                         const SkBitmap& drag_image,
+                                         const gfx::Vector2d& drag_image_offset,
+                                         ui::mojom::DragEventSource source) {}
+
+void MusDemoInternal::OnWmMoveDragImage(const gfx::Point& cursor_location) {}
+
+void MusDemoInternal::OnWmDestroyDragImage() {}
+
 void MusDemoInternal::OnWmWillCreateDisplay(const display::Display& display) {
   AddPrimaryDisplay(display);
 }
 
 void MusDemoInternal::OnWmNewDisplay(
     std::unique_ptr<aura::WindowTreeHostMus> window_tree_host,
     const display::Display& display) {
   AppendWindowTreeData(base::MakeUnique<WindowTreeData>(kSquareSize));
   InitWindowTreeData(std::move(window_tree_host));
 }
@@ skipping 28 matching lines @@
     const std::vector<gfx::Rect>& additional_client_areas) {}
 
 bool MusDemoInternal::IsWindowActive(aura::Window* window) {
   return false;
 }
 
 void MusDemoInternal::OnWmDeactivateWindow(aura::Window* window) {}
 
 }  // namespace demo
 }  // namespace ui