No longer trigger signin errors on connection_failed for sync.
If ProfileSyncService gets a transient network error trying to contact the
backend, we no longer treat this as a fatal signin error.
Also, we no longer display a "wait for the backend to startup" spinner in cases
where we know the spinner will immediately be dismissed, to avoid a gnarly
infinite loop in the UI code.
BUG=244769
Review URL: https://chromiumcodereview.appspot.com/
16173006
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@203968 0039d316-1c4b-4281-b951-d872f2087c98