Mark services in password-fail as PassPhrase Required

Mark services in password-fail as PassPhrase Required

If the service is currently failed due to a PassPhrase error,
return "True" for the PassPhrase Requred property.  Use a cached
copy of the previous value to properly gate sending signals.  Also
provide damping so spurious signals are not sent.

BUG=chromium-os:10135
TEST=Manual -- observe list-services while replicating conditions of
10135

Change-Id: Ib999360dabf47c637f660b8744afb85c4d59ad5f

Committed: http://chrome-svn/viewvc/chromeos?view=rev&revision=b22ddeb

[Paul Stewart, 2011-03-31 19:32:45]

Is this along the lines of what you wanted Steven?  Sam, could you look over
this to see if this is the way you want this addressed?

[stevenjb, 2011-04-06 02:11:58]

That looks right, thanks. LGTM.

[Paul Stewart, 2011-04-06 03:14:55]

On 2011/04/06 02:11:58, Steven Bennetts wrote:
> That looks right, thanks. LGTM.

Unfortunately it's not quite right.  I've had an offline chat with Sam, and
there are some subtleties that need to be addressed.  I will hopefully be able
to put a revision to this CL up tomorrow.

[Paul Stewart, 2011-04-08 04:13:50]

PTAL.  This version uses a cached value to gate changes as well as damping to
prevent spurious wiggles.

[Paul Stewart, 2011-04-08 17:53:57]

...and after a flurry of discussion on the issue, we're right back to the
original CL.  PTAL.

[Sam Leffler, 2011-04-08 17:59:21]

LGTM (and thank you for all the back-and-fort)