Reorder browser list on workspace switch

ui/display/desktop.h

+// Copyright 2016 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_DISPLAY_DESKTOP_H_
+#define UI_DISPLAY_DESKTOP_H_
+
+#include "base/lazy_instance.h"
+#include "base/observer_list.h"
+#include "ui/display/display_export.h"
+
+namespace display {
+
+class DesktopObserver;
+
+class DISPLAY_EXPORT Desktop {
+ public:
+  // Retreives the Desktop singleton.
+  static Desktop* GetDesktop();

[Tom (Use chromium acct), 2016/07/06 18:19:11]

GetDesktop currently is not used anywhere, but ChromeBrowserMainExtraPartsX11
calls SetDesktopInstance

Should we just get rid of these?

[sky, 2016/07/06 20:33:05]

Yes. Here is what I recommend doing:
. remove all changes to ui/display.
. X11DesktopHandler  gets an AddObserver function. The observer is
X11DesktopHandlerObserver and defined in its own header in
ui/views/widget/desktop_aura/x11_desktop_handler_observer.h.
. Make ChromeBrowserMainExtraPartsViewsLinux implement X11DesktopHandlerObserver
 (or have it create a class that implement X11DesktopHandlerObserver , I'm fine
either way).

[Tom (Use chromium acct), 2016/07/06 22:29:16]

Done.

+
+  // Sets the Desktop singleton instance.
+  static void SetDesktopInstance(Desktop* desktop);
+
+  void AddObserver(DesktopObserver* observer);
+  void RemoveObserver(DesktopObserver* observer);
+
+ protected:
+  Desktop();
+  ~Desktop();
+
+  base::ObserverList<DesktopObserver> desktop_observer_list_;
+};
+
+}  // namespace display
+
+#endif