文件创建时的Chrome App SecurityError

Question

我有以下代码:

chrome.runtime.getPackageDirectoryEntry(function(directoryEntry) 
{
    directoryEntry.getFile("files/test.txt", {create: true, exclusive: false}, function(fileEntry) 
    {
        console.log(fileEntry);
    },
    function(error)
    {
        console.log(error);
    });
});

如果文件不存在且create为true,则会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.出错.但如果确实存在且create为false,则可以访问该文件.

我究竟做错了什么？