mash: Use the new mus drag and drop API to get drag working in mash.

services/ui/public/cpp/window.cc

 // 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.
 
 #include "services/ui/public/cpp/window.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <set>
@@ skipping 463 matching lines @@
   else
     callback.Run(false);
 }
 
 void Window::RequestClose() {
   if (client_)
     client_->RequestClose(this);
 }
 
 void Window::PerformDragDrop(
-    int drag_pointer,
     const std::map<std::string, std::vector<uint8_t>>& drag_data,
     int drag_operation,
     const gfx::Point& cursor_location,
     const SkBitmap& bitmap,
     const base::Callback<void(bool, uint32_t)>& callback) {
-  client_->PerformDragDrop(this, drag_pointer, drag_data, drag_operation,
-                           cursor_location, bitmap, callback);
+  client_->PerformDragDrop(this, drag_data, drag_operation, cursor_location,
+                           bitmap, callback);
 }
 
 void Window::CancelDragDrop() {
   client_->CancelDragDrop(this);
 }
 
 void Window::PerformWindowMove(mojom::MoveLoopSource source,
                                const gfx::Point& cursor_location,
                                const base::Callback<void(bool)>& callback) {
   client_->PerformWindowMove(this, source, cursor_location, callback);
@@ skipping 422 matching lines @@
     notifier->NotifyWindowReordered();
 
   return true;
 }
 
 // static
 Window** Window::GetStackingTarget(Window* window) {
   return &window->stacking_target_;
 }
 }  // namespace ui