Pass in the time of the user's last activity timestamp with the NET_ACTIVE_WINDOW event

ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h

Index: ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h
diff --git a/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h b/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h
index 36868972bd660c886fd4194669b89514765964cb..1b28d03368c572ba6af08ecc290e64dcb11d795e 100644
--- a/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h
+++ b/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h
@@ -172,6 +172,9 @@ class VIEWS_EXPORT DesktopWindowTreeHostX11
   // Called when |xwindow_|'s _NET_FRAME_EXTENTS property is updated.
   void OnFrameExtentsUpdated();
 
+  // Updates |xwindow_|'s _NET_WM_USER_TIME if |xwindow_| is active.
+  void UpdateWMUserTime(const ui::PlatformEvent& event);
+
   // Sends a message to the x11 window manager, enabling or disabling the
   // states |state1| and |state2|.
   void SetWMSpecState(bool enabled, ::Atom state1, ::Atom state2);