Remove the singleton instance get/delete methods from RootWindow (yay)

ui/aura/root_window_host_linux.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/aura/root_window_host_linux.h"
 
 #include <X11/cursorfont.h>
 #include <X11/extensions/XInput2.h>
 #include <algorithm>
 
@@ skipping 287 matching lines @@
                     ExposureMask | VisibilityChangeMask |
                     StructureNotifyMask | PropertyChangeMask |
                     PointerMotionMask;
   XSelectInput(xdisplay_, xwindow_, event_mask);
   XSelectInput(xdisplay_, x_root_window_, StructureNotifyMask);
   XFlush(xdisplay_);
 
   if (base::MessagePumpForUI::HasXInput2())
     ui::TouchFactory::GetInstance()->SetupXI2ForXWindow(xwindow_);
 
-  MessageLoopForUI::current()->AddDestructionObserver(this);
-
   // Initialize invisible cursor.
   char nodata[] = { 0, 0, 0, 0, 0, 0, 0, 0 };
   XColor black;
   black.red = black.green = black.blue = 0;
   Pixmap blank = XCreateBitmapFromData(xdisplay_, xwindow_,
                                        nodata, 8, 8);
   invisible_cursor_ = XCreatePixmapCursor(xdisplay_, blank, blank,
                                           &black, &black, 0, 0);
   if (RootWindow::hide_host_cursor())
     XDefineCursor(xdisplay_, x_root_window_, invisible_cursor_);
 }
 
 RootWindowHostLinux::~RootWindowHostLinux() {
   static_cast<DispatcherLinux*>(Env::GetInstance()->GetDispatcher())->
       RootWindowHostDestroying(xwindow_, x_root_window_);
   XDestroyWindow(xdisplay_, xwindow_);
 
   // Clears XCursorCache.
   ui::GetXCursor(ui::kCursorClearXCursorCache);
 
   XFreeCursor(xdisplay_, invisible_cursor_);
-
-  MessageLoopForUI::current()->RemoveDestructionObserver(this);
 }
 
 base::MessagePumpDispatcher::DispatchStatus RootWindowHostLinux::Dispatch(
     XEvent* xev) {
   bool handled = false;
 
   // See crbug.com/109884.
   // CheckXEventForConsistency(xev);
 
   switch (xev->type) {
@@ skipping 274 matching lines @@
       root_window_->ConvertPointToNativeScreen(&point);
       xevent.xmotion.x_root = point.x();
       xevent.xmotion.y_root = point.y();
     }
     default:
       break;
   }
   XSendEvent(xdisplay_, xwindow_, False, 0, &xevent);
 }
 
-void RootWindowHostLinux::WillDestroyCurrentMessageLoop() {
-  aura::RootWindow::DeleteInstance();
-}
-
 bool RootWindowHostLinux::IsWindowManagerPresent() {
   // Per ICCCM 2.8, "Manager Selections", window managers should take ownership
   // of WM_Sn selections (where n is a screen number).
   ::Atom wm_s0_atom = XInternAtom(xdisplay_, "WM_S0", False);
   return XGetSelectionOwner(xdisplay_, wm_s0_atom) != None;
 }
 
 void RootWindowHostLinux::SetCursorInternal(gfx::NativeCursor cursor) {
   ::Cursor xcursor =
       cursor == kCursorNone ?
       invisible_cursor_ :
       ui::GetXCursor(CursorShapeFromNative(cursor));
   XDefineCursor(xdisplay_, xwindow_, xcursor);
 }
 
 // static
 RootWindowHost* RootWindowHost::Create(const gfx::Rect& bounds) {
   return new RootWindowHostLinux(bounds);
 }
 
 // static
 gfx::Size RootWindowHost::GetNativeScreenSize() {
   ::Display* xdisplay = base::MessagePumpX::GetDefaultXDisplay();
   return gfx::Size(DisplayWidth(xdisplay, 0), DisplayHeight(xdisplay, 0));
 }
 
 }  // namespace aura