Make File-Picker modal on Linux

ui/views/widget/desktop_aura/x11_desktop_handler.h

Index: ui/views/widget/desktop_aura/x11_desktop_handler.h
diff --git a/ui/views/widget/desktop_aura/x11_desktop_handler.h b/ui/views/widget/desktop_aura/x11_desktop_handler.h
index c704bbaecfec917aec2f9126a14a69834260a463..0c2135b07b6304ee0591796e8c7391df4b88fb8d 100644
--- a/ui/views/widget/desktop_aura/x11_desktop_handler.h
+++ b/ui/views/widget/desktop_aura/x11_desktop_handler.h
@@ -12,6 +12,7 @@
 #include <vector>
 
 #include "ui/aura/env_observer.h"
+#include "ui/aura/scoped_window_targeter.h"
 #include "ui/events/platform/platform_event_dispatcher.h"
 #include "ui/gfx/x/x11_atom_cache.h"
 #include "ui/gfx/x/x11_types.h"
@@ -64,6 +65,9 @@ class VIEWS_EXPORT X11DesktopHandler : public ui::PlatformEventDispatcher,
   void OnWindowInitialized(aura::Window* window) override;
   void OnWillDestroyEnv() override;
 
+  // Make dialog modal.
+  void SetModalDialog(XID dialog);
+
  private:
   enum ActiveState {
     ACTIVE,
@@ -101,6 +105,10 @@ class VIEWS_EXPORT X11DesktopHandler : public ui::PlatformEventDispatcher,
 
   bool wm_supports_active_window_;
 
+  XID modal_dialog_xid_;
+
+  scoped_ptr<aura::ScopedWindowTargeter> scoped_targeter_;
+
   DISALLOW_COPY_AND_ASSIGN(X11DesktopHandler);
 };