Make GetRootWindow() return a Window instead of a RootWindow.

ui/views/widget/desktop_aura/desktop_drag_drop_client_aurax11.cc

 // Copyright (c) 2012 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 "ui/views/widget/desktop_aura/desktop_drag_drop_client_aurax11.h"
 
 #include <X11/Xatom.h>
 
 #include "base/event_types.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 663 matching lines @@
 void DesktopDragDropClientAuraX11::OnMoveLoopEnded() {
   target_current_context_.reset();
 }
 
 void DesktopDragDropClientAuraX11::DragTranslate(
     const gfx::Point& root_window_location,
     scoped_ptr<ui::OSExchangeData>* data,
     scoped_ptr<ui::DropTargetEvent>* event,
     aura::client::DragDropDelegate** delegate) {
   gfx::Point root_location = root_window_location;
-  root_window_->GetRootWindow()->ConvertPointFromNativeScreen(&root_location);
+  root_window_->GetDispatcher()->ConvertPointFromNativeScreen(&root_location);
   aura::Window* target_window =
       root_window_->GetEventHandlerForPoint(root_location);
   bool target_window_changed = false;
   if (target_window != target_window_) {
     if (target_window_)
       NotifyDragLeave();
     target_window_ = target_window;
     if (target_window_)
       target_window_->AddObserver(this);
     target_window_changed = true;
@@ skipping 219 matching lines @@
   // GdkEvent about the failed drag. (And sending this message doesn't appear
   // to go through normal xlib machinery, but instead passes through the low
   // level xProto (the x11 wire format) that I don't understand.
   //
   // I'm unsure if I have to jump through those hoops, or if XSendEvent is
   // sufficient.
   XSendEvent(xdisplay_, xid, False, 0, xev);
 }
 
 }  // namespace views