[prefs] Fix Crash and add Aliases

This change fixes GetMutableUserPref() to not return values of the wrong
type and adds base::debug::Alias statements to figure out for which
paths the type does not match.

Bug: 859477
Change-Id: I2a076f1020b610ca42469d891ef652889c17bf72
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1621167
Reviewed-by: Dominic Battré <battre@chromium.org>
Commit-Queue: Jan Wilken Dörrie <jdoerrie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#661691}
1 file changed