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

services/ui/public/cpp/window.cc

Index: services/ui/public/cpp/window.cc
diff --git a/services/ui/public/cpp/window.cc b/services/ui/public/cpp/window.cc
index 81f07e148d87aba1b4f5beadab8273de636d86c7..4257c0c4ec169f689b64e879cce47d65b1c6e554 100644
--- a/services/ui/public/cpp/window.cc
+++ b/services/ui/public/cpp/window.cc
@@ -481,14 +481,13 @@ void Window::RequestClose() {
 }
 
 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() {