Fix X11DesktopHandler::ActivateWindow on Unity for known user gestures

ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc

Index: ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
diff --git a/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc b/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
index cfd6d1065731bdd5c52bb2c3af7295b795b9a198..0407bf7fcd0dc4140bd2d46fbad745b8f84cd372 100644
--- a/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
+++ b/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
@@ -318,6 +318,10 @@ void DesktopWindowTreeHostWin::Activate() {
   message_handler_->Activate();
 }
 
+void DesktopWindowTreeHostWin::ActivateForUserGesture() {
+  Activate();
+}
+
 void DesktopWindowTreeHostWin::Deactivate() {
   message_handler_->Deactivate();
 }