SyncService::CanSyncStart: return false after an unrecoverable error

This should make no difference whatsoever in practice (in case of an
unrecoverable error, we won't try to start up again anyway), it just
makes things a bit simpler to reason about.

Bug: 839834
Change-Id: Ie3ac83b172f9fab100b1a176421025aa1f3699dc
Reviewed-on: https://chromium-review.googlesource.com/1138252
Commit-Queue: Marc Treib <treib@chromium.org>
Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575355}
2 files changed