Moved the handling of the initial passphrase into SyncSetupFlow.
This makes the passphrase handling more uniform across platforms, which should
result in fewer bugs on non-desktop-ui platforms and also pave the way for
OAuth integration.
Also updated the "autostart sync" code to enable it to be used on non-cros platforms.
BUG=
95002,
91443,
82221
TEST=run through signin/setup test cases
Committed:
http://src.chromium.org/viewvc/chrome?view=rev&revision=99504