- Electron version:
  1.3.3
- Operating system:
  OSX El Capitan

``` javascript
      function cbError(e) {
         console.error('failure', e);
      }

      navigator.webkitPersistentStorage.requestQuota( 10 * 1024* 1024, function(granted) {
        webkitRequestFileSystem(PERSISTENT, granted, cb, cbError);
      },
      cbError)
```

webkitRequestFileSystem is failing with:

```
FileError {code: 2, name: "SecurityError", message: "It was determined that certain files are unsafe fo… too many calls are being made on file resources."}code: 2message: "It was determined that certain files are unsafe for access within a Web application, or that too many calls are being made on file resources."name: "SecurityError"__proto__: FileError
```

This page is being served from a custom:// scheme if that matters.

atom/browser/atom_browser_client.cc
#include "atom/browser/atom_browser_client.h"
#if defined(OS_WIN)
#include <shlobj.h>
#endif
#include "atom/browser/api/atom_api_app.h"
#include "atom/browser/atom_access_token_store.h"
#include "atom/browser/atom_browser_context.h"
#include "atom/browser/atom_browser_main_parts.h"
#include "atom/browser/atom_quota_permission_context.h"
#include "atom/browser/atom_resource_dispatcher_host_delegate.h"
#include "atom/browser/atom_speech_recognition_manager_delegate.h"
#include "atom/browser/native_window.h"
#include "atom/browser/web_contents_permission_helper.h"
#include "atom/browser/web_contents_preferences.h"
#include "atom/browser/window_list.h"
#include "atom/common/options_switches.h"
#include "base/command_line.h"
#include "base/files/file_util.h"