Linux Aura: Use managed tab dragging when possible (Reland)

ui/views/widget/desktop_aura/x11_window_event_filter.h

Index: ui/views/widget/desktop_aura/x11_window_event_filter.h
diff --git a/ui/views/widget/desktop_aura/x11_window_event_filter.h b/ui/views/widget/desktop_aura/x11_window_event_filter.h
index 2b80c8b5fbd0292793908674cff54dd98773899c..f0d2a93e7c5159bc1230ccfa80f85c0c04215dc6 100644
--- a/ui/views/widget/desktop_aura/x11_window_event_filter.h
+++ b/ui/views/widget/desktop_aura/x11_window_event_filter.h
@@ -11,7 +11,6 @@
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
 #include "ui/events/event_handler.h"
-#include "ui/gfx/x/x11_atom_cache.h"
 #include "ui/gfx/x/x11_types.h"
 #include "ui/views/views_export.h"
 
@@ -55,11 +54,6 @@ class VIEWS_EXPORT X11WindowEventFilter : public ui::EventHandler {
   XDisplay* xdisplay_;
   ::Window xwindow_;
 
-  // The native root window.
-  ::Window x_root_window_;
-
-  ui::X11AtomCache atom_cache_;
-
   DesktopWindowTreeHost* window_tree_host_;
 
   // The non-client component for the target of a MouseEvent. Mouse events can