Fix disabling sync in Chrome for Android.

Fix disabling sync in Chrome for Android.

A change in http://crrev.com/612573006 to ProfileSyncServiceAndroid
caused isSyncInitialized() to check whether sync was active instead of
whether the backend was initialized. This broke something in the disable
sync flow; probably an assertion.

BUG=423450
Committed: https://crrev.com/825174fcd3483b1317cd8021d3fe57589a753abc
Cr-Commit-Position: refs/heads/master@{#300397}

[maxbogue, 2014-10-20 22:31:47]

maxbogue@chromium.org changed reviewers:
+ zea@chromium.org

[Nicolas Zea, 2014-10-20 22:46:26]

LGTM if the manual test works. Would be good to file a bug to add tests for this
too,

[maxbogue, 2014-10-20 23:56:28]

The CQ bit was checked by maxbogue@chromium.org

[commit-bot: I haz the power, 2014-10-20 23:59:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/666033002/1

[commit-bot: I haz the power, 2014-10-21 01:35:20]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-10-21 01:37:17]

Patchset 1 (id:??) landed as
https://crrev.com/825174fcd3483b1317cd8021d3fe57589a753abc
Cr-Commit-Position: refs/heads/master@{#300397}