Make File-Picker modal on Linux

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 09b5993fb8c9d61d79ea1ea3e8e3be72c2f4079b..20399df380b17d04225a0a04dbeb23135b06670b 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
@@ -13,6 +13,7 @@
 #include "base/cancelable_callback.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
+#include "ui/aura/scoped_window_targeter.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/base/cursor/cursor_loader_x11.h"
 #include "ui/events/platform/platform_event_dispatcher.h"
@@ -85,6 +86,16 @@ class VIEWS_EXPORT DesktopWindowTreeHostX11
   // internal list of open windows.
   static void CleanUpWindowList(void (*func)(aura::Window* window));
 
+  // Disables event listening to make |dialog| modal.
+  void DisableEventListening(XID dialog);
+
+  // Enables event listening after closing |dialog|.
+  void EnableEventListening();
+
+  // Returns XID of dialog currently displayed. When it returns 0,
+  // there is no dialog on the host window.
+  const XID GetModalDialog();
+
  protected:
   // Overridden from DesktopWindowTreeHost:
   void Init(aura::Window* content_window,
@@ -351,6 +362,10 @@ class VIEWS_EXPORT DesktopWindowTreeHostX11
 
   base::CancelableCallback<void()> delayed_resize_task_;
 
+  scoped_ptr<aura::ScopedWindowTargeter> targeter_for_modal_;
+
+  XID modal_dialog_xid_;
+
   base::WeakPtrFactory<DesktopWindowTreeHostX11> close_widget_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DesktopWindowTreeHostX11);