Version: 55, probably before but my device is hosed
OS: Chrome

In CrOS guest mode, prefs cannot be fetched:

1. Browse as Guest (in CrOS for Linux, use --incognito --bwsi --login-profile=user '--login-user=$guest')
2. chrome://md-settings

[116924:116924:0919/203146:ERROR:CONSOLE(0)] "Error in response to settingsPrivate.getAllPrefs: TypeError: Cannot read property 'forEach' of undefined", source: chrome://md-settings/ (0)
[116924:116924:0919/203146:ERROR:CONSOLE(0)] "Unchecked runtime.lastError while running settingsPrivate.getAllPrefs: delegate is null", source: chrome://md-settings/ (0)
[116924:116924:0919/203146:ERROR:CONSOLE(0)] "Unchecked runtime.lastError while running settingsPrivate.getDefaultZoomPercent: delegate is null", source: chrome://md-settings/ (0)

This effectively breaks most things.