Revert 124461 - Remove the singleton instance get/delete methods from RootWindow (yay)

ui/aura/root_window_host_linux.h

 // 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.
 
 #ifndef UI_AURA_ROOT_WINDOW_HOST_LINUX_H_
 #define UI_AURA_ROOT_WINDOW_HOST_LINUX_H_
 #pragma once
 
 #include <X11/Xlib.h>
 
 // Get rid of a macro from Xlib.h that conflicts with Aura's RootWindow class.
 #undef RootWindow
 
 #include "base/message_loop.h"
 #include "ui/aura/root_window_host.h"
 #include "ui/gfx/rect.h"
 
 namespace aura {
 
-class RootWindowHostLinux : public RootWindowHost {
+class RootWindowHostLinux : public RootWindowHost,
+                            public MessageLoop::DestructionObserver {
  public:
   explicit RootWindowHostLinux(const gfx::Rect& bounds);
   virtual ~RootWindowHostLinux();
 
   // Handles an event targeted at this host's window.
   base::MessagePumpDispatcher::DispatchStatus Dispatch(XEvent* xev);
 
  private:
   // RootWindowHost Overrides.
   virtual void SetRootWindow(RootWindow* root_window) OVERRIDE;
   virtual gfx::AcceleratedWidget GetAcceleratedWidget() OVERRIDE;
   virtual void Show() OVERRIDE;
   virtual void ToggleFullScreen() OVERRIDE;
   virtual gfx::Size GetSize() const OVERRIDE;
   virtual void SetSize(const gfx::Size& size) OVERRIDE;
   virtual gfx::Point GetLocationOnNativeScreen() const OVERRIDE;
   virtual void SetCapture() OVERRIDE;
   virtual void ReleaseCapture() OVERRIDE;
   virtual void SetCursor(gfx::NativeCursor cursor_type) OVERRIDE;
   virtual void ShowCursor(bool show) OVERRIDE;
   virtual gfx::Point QueryMouseLocation() OVERRIDE;
   virtual bool ConfineCursorToRootWindow() OVERRIDE;
   virtual void UnConfineCursor() OVERRIDE;
   virtual void MoveCursorTo(const gfx::Point& location) OVERRIDE;
   virtual void PostNativeEvent(const base::NativeEvent& event) OVERRIDE;
 
+  // MessageLoop::DestructionObserver Overrides.
+  virtual void WillDestroyCurrentMessageLoop() OVERRIDE;
+
   // Returns true if there's an X window manager present... in most cases.  Some
   // window managers (notably, ion3) don't implement enough of ICCCM for us to
   // detect that they're there.
   bool IsWindowManagerPresent();
 
   // Sets the cursor on |xwindow_| to |cursor|.  Does not check or update
   // |current_cursor_|.
   void SetCursorInternal(gfx::NativeCursor cursor);
 
   RootWindow* root_window_;
@@ skipping 16 matching lines @@
 
   // The bounds of |xwindow_|.
   gfx::Rect bounds_;
 
   DISALLOW_COPY_AND_ASSIGN(RootWindowHostLinux);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_ROOT_WINDOW_HOST_LINUX_H_