[Aura] Support always-on-top top level window.

ui/aura/desktop_host_linux.cc

 // Copyright (c) 2011 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/aura/desktop_host.h"
 
 #include <X11/cursorfont.h>
 #include <X11/Xlib.h>
 
 // Get rid of a macro from Xlib.h that conflicts with Aura's RootWindow class.
@@ skipping 267 matching lines @@
                     PointerMotionMask;
   XSelectInput(xdisplay_, xwindow_, event_mask);
   XFlush(xdisplay_);
 
   if (base::MessagePumpForUI::HasXInput2())
     ui::TouchFactory::GetInstance()->SetupXI2ForXWindow(xwindow_);
 }
 
 DesktopHostLinux::~DesktopHostLinux() {
   XDestroyWindow(xdisplay_, xwindow_);
+
+  // Clears XCursorCache.
+  ui::GetXCursor(ui::kCursorClearXCursorCache);
 }
 
 base::MessagePumpDispatcher::DispatchStatus DesktopHostLinux::Dispatch(
     XEvent* xev) {
   bool handled = false;
   switch (xev->type) {
     case Expose:
       desktop_->Draw();
       handled = true;
       break;
@@ skipping 190 matching lines @@
   return new DesktopHostLinux(bounds);
 }
 
 // static
 gfx::Size DesktopHost::GetNativeDisplaySize() {
   ::Display* xdisplay = base::MessagePumpX::GetDefaultXDisplay();
   return gfx::Size(DisplayWidth(xdisplay, 0), DisplayHeight(xdisplay, 0));
 }
 
 }  // namespace aura