* Output of `node_modules/.bin/electron --version`: 3.0.10, 4.0.0-beta.7
* Operating System (Platform and Version): Ubuntu 18.04
* Output of `node_modules/.bin/electron --version` on last known working Electron version (if applicable): N/A

**Expected Behavior**
When picking a file to upload, the file picker should show a preview of the file when applicable

**Actual behavior**
It does not show a preview...

Chrome shows a preview of the image (tested with 70 and 69).
![chrome](https://user-images.githubusercontent.com/103586/48838688-01b4f280-ed81-11e8-8b38-16d7cbab1f22.png)

Electron shows no preview
![electron](https://user-images.githubusercontent.com/103586/48838699-08dc0080-ed81-11e8-8611-6a199fba23f8.png)


**To Reproduce**
Nothing special, click on a file upload form element...
```html
<input type="file" />
```
Example here: https://cgi-lib.berkeley.edu/ex/fup.html
atom/browser/ui/file_dialog_gtk.cc
private:
  void AddFilters(const Filters& filters);
  atom::NativeWindowViews* parent_;
  atom::UnresponsiveSuppressor unresponsive_suppressor_;
  GtkWidget* dialog_;
  Filters filters_;
  SaveDialogCallback save_callback_;
  OpenDialogCallback open_callback_;
  DISALLOW_COPY_AND_ASSIGN(FileChooserDialog);
};
void FileChooserDialog::OnFileDialogResponse(GtkWidget* widget, int response) {
  gtk_widget_hide(dialog_);
  if (!save_callback_.is_null()) {
    if (response == GTK_RESPONSE_ACCEPT)
      save_callback_.Run(true, GetFileName());
    else
      save_callback_.Run(false, base::FilePath());
  } else if (!open_callback_.is_null()) {
    if (response == GTK_RESPONSE_ACCEPT)
      open_callback_.Run(true, GetFileNames());
    else
      open_callback_.Run(false, std::vector<base::FilePath>());
  }
  delete this;
}
void FileChooserDialog::AddFilters(const Filters& filters) {