Use current gtk dialogs in linux_aura.

ui/base/linux_ui.h

Index: ui/base/linux_ui.h
diff --git a/ui/base/linux_ui.h b/ui/base/linux_ui.h
index 53327207390f384d2b277c1741a00bee2ed9c10f..3fb34e5523a251c35c4ab83b8edd0e950dae03ab 100644
--- a/ui/base/linux_ui.h
+++ b/ui/base/linux_ui.h
@@ -5,6 +5,7 @@
 #ifndef UI_BASE_LINUX_UI_H_
 #define UI_BASE_LINUX_UI_H_
 
+#include "ui/base/dialogs/select_file_dialog.h"
 #include "ui/base/ui_export.h"
 #include "third_party/skia/include/core/SkColor.h"
 
@@ -16,6 +17,7 @@ class Image;
 }
 
 namespace ui {
+class SelectFilePolicy;
 
 // Adapter class with targets to render like different toolkits. Set by any
 // project that wants to do linux desktop native rendering.
@@ -42,6 +44,11 @@ class UI_EXPORT LinuxUI {
   virtual bool UseNativeTheme() const = 0;
   virtual gfx::Image* GetThemeImageNamed(int id) const = 0;
   virtual bool GetColor(int id, SkColor* color) const = 0;
+
+  // Returns a native file selection dialog.
+  virtual SelectFileDialog* CreateSelectFileDialog(
+      SelectFileDialog::Listener* listener,
+      SelectFilePolicy* policy) const = 0;
 };
 
 }  // namespace ui