- Electron version: 1.2.2
- Operating system: Linux

This is a problem only in linux. It works in OSX.

``` javascript
win.hide()
win.capturePage(function(img){
 // never called
})
```

shell/browser/api/electron_api_web_contents.cc
auto file_system_paths = GetAddedFileSystemPaths(GetDevToolsWebContents());
  if (file_system_paths.empty()) {
    base::ListValue empty_file_system_value;
    inspectable_ontents_->CallClientFunction(
        "DevToolsAPI.fileSystemsLoaded", &empty_file_system_value, nullptr,
        nullptr);
    return;
  }
  std::vector<FileSystem> file_systems;
  for (const auto& file_system_path : file_system_paths) {
    base::FilePath path =
        base::FilePath::FromUTF8Unsafe(file_system_path.first);
    std::string file_system_id =
        RegisterFileSystem(GetDevToolsWebContents(), path);
    FileSystem file_system =
        CreateFileSystemStruct(GetDevToolsWebContents(), file_system_id,
                               file_system_path.first, file_system_path.second);
    file_systems.push_back(file_system);
  }
  base::ListValue file_system_value;
  for (const auto& file_system : file_systems)
    file_system_value.Append(CreateFileSystemValue(file_system));
  inspectable_ontents_->CallClientFunction(
      "DevToolsAPI.fileSystemsLoaded", &file_system_value, nullptr, nullptr);
}
void WebContents::DevToolsAddFileSystem(