* Electron version: 8.0.0
* Operating system: Linux - Fedora 31 - Kernel 5.4.13-201.fc31.x86_64

### Expected behavior
The local store should persist items even though the app is terminated as soon as the item was added.

### Actual behavior
If the app is terminated in less than 2 seconds after an item is added to local storage, the value is not available after the app is reopened.

### How to reproduce
1. Create a new electron app 
(I used the quick start from the website git clone https://github.com/electron/electron-quick-start)

0. Run the app using `npm start`

0. Run a JavaScript code that adds a new key/value pair to localStorage
````
localStorage.setItem("my-key", "my-value")
````

0. Within 3 seconds, terminate the app (killing the process or pressing Ctrl + C)
NOTE: If the app is closed properly (pressing Alt + F4 or click on the "X"), this issue does not occur.

0. Run the app again

0. Check for the localStorage items
````
localStorage.getItem("my-key")
````
Or in the Application tab from Developer Tools.

Both cases are not available neither the key nor the value
shell/browser/electron_browser_main_parts.cc
base::FilePath path;
  if (base::PathService::Get(DIR_APP_DATA, &path))
    return;
  std::unique_ptr<base::Environment> env(base::Environment::Create());
  path = base::nix::GetXDGDirectory(env.get(), base::nix::kXdgConfigHomeEnvVar,
                                    base::nix::kDotConfigDir);
  base::PathService::Override(DIR_APP_DATA, path);
}
void UpdateDarkThemeSetting() {
  float bg = color_utils::GetRelativeLuminance(gtk::GetBgColor("GtkLabel"));
  float fg = color_utils::GetRelativeLuminance(gtk::GetFgColor("GtkLabel"));
  bool is_dark = fg > bg;
  
  
  ui::NativeTheme::GetInstanceForNativeUi()->set_use_dark_colors(is_dark);
  
  ui::NativeTheme::GetInstanceForWeb()->set_use_dark_colors(is_dark);
}
#endif
}  
#if defined(OS_LINUX)
class DarkThemeObserver : public ui::NativeThemeObserver {