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

 // 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_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_WINDOW_TREE_HOST_X11_H_
 #define UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_WINDOW_TREE_HOST_X11_H_
 
 #include <X11/extensions/shape.h>
 #include <X11/Xlib.h>
 
@@ skipping 154 matching lines @@
   // Creates an aura::WindowEventDispatcher to contain the |content_window|,
   // along with all aura client objects that direct behavior.
   aura::WindowEventDispatcher* InitDispatcher(const Widget::InitParams& params);
 
   // Called when |xwindow_|'s _NET_WM_STATE property is updated.
   void OnWMStateUpdated();
 
   // 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);
 
   // Checks if the window manager has set a specific state.
   bool HasWMSpecProperty(const char* property) const;
 
   // Sets whether the window's borders are provided by the window manager.
   void SetUseNativeFrame(bool use_native_frame);
 
@@ skipping 133 matching lines @@
   // attention to the window or completely ignore the hint. We stop flashing
   // the frame when |xwindow_| gains focus or handles a mouse button event.
   bool urgency_hint_set_;
 
   DISALLOW_COPY_AND_ASSIGN(DesktopWindowTreeHostX11);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_WINDOW_TREE_HOST_X11_H_