Revert 241977 "Add hook for extension to check sync status."

Revert 241977 "Add hook for extension to check sync status."

Suspected to cause use-after-free on ChromeOS/Linux bot.
http://build.chromium.org/p/chromium.memory/builders/Linux%20Chromium%20OS%20ASAN%20Tests%20%282%29/builds/15076/steps/browser_tests/logs/GetSyncCategoriesWithoutPassphraseSynchronous

Might be test-only, but reverting this as u-a-f doesn't sound good

> Add hook for extension to check sync status.
> 
> Adds a new function to preferencesPrivate that returns a list of
> unencrypted sync categories. Also changes preferencesPrivate to use a
> whitelist instead of being restricted to component extensions.
> 
> BUG=326678
> 
> Review URL: https://codereview.chromium.org/118413003

TBR=rfevang@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=242038

[kinuko, 2013-12-20 07:55:58]

Committed patchset #1 manually as r242038.

[kinuko, 2013-12-20 09:30:57]

CrOS ASAN bot has become green after this revert.