Browser: add valid missing fragments (fixes FC)

WebsiteSettingsFragment and DebugPreferencesFragment are also valid
fragments.

Change-Id: I4e945a3b9de62879afcc621fb97811e75ca53cb1
Browser: disable incognito mode

Chromium Webview does not support incognito mode which will result
in force close, disabling for now.

Change-Id: I501a609f94c115b9a9d1755ef0ea73eb9b29c823
Browser: fix pie crash

Introduced in 5623a091605bf1d88687dc589a61ee6b54c554fe.

Change-Id: I83f44be84fb70e2777ab1414c0af2a368c435fb8