According to the docs the "syncFileSystem" permission needs to be added to the manifest to enable the syncFileSystem API.
I found this because when I cloned the NoteAS app I was getting exceptions in window.onload() and chrome.syncFileSystem.onFileStatusChanged.addListener() calls. Adding the permission to my manifest fixed the exceptions.
According to the docs the "syncFileSystem" permission needs to be added to the manifest to enable the syncFileSystem API.
I found this because when I cloned the NoteAS app I was getting exceptions in window.onload() and chrome.syncFileSystem.onFileStatusChanged.addListener() calls. Adding the permission to my manifest fixed the exceptions.