Remove download_manager_ CHECK in ~SavePackage

Remove download_manager_ CHECK in ~SavePackage

download_manager_ can non-null if SavePackage is created and destroyed without Init() being called.
This CHECK was originally introduced when SavePackage was an observer of the DownloadManager.

BUG=91884
TEST=NONE
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=95851

[achuithb, 2011-08-08 18:43:37]

Looks like rdsmith is still on vacation.

This incorrect CHECK is a R15 top crasher and it looks like we need a resolution
by eod today for the dev build later in the week. So please prioritize this
review accordingly. Thanks!

[Paweł Hajdan Jr., 2011-08-08 19:05:01]

LGTM

Achuith explained the details to me. I believe that even when the CHECK was
added it was not really validating the property it was claiming to validate.
Later, the CL was further changed (while still in review) in a way that I
believe invalidated the CHECK completely, and then got committed.

Achuith: as a follow-up, could you please write a test that would trigger this
CHECK condition in case it was still there? We should have issues like that
detected by unit tests, not by releasing software to users and seeing "crashes".

[ahendrickson, 2011-08-08 19:08:02]

LGTM.

[achuithb, 2011-08-08 19:11:46]

Pawel: The test you suggest should be simple. I'll have a CL with it for review
this week. (Thanks for swinging by)

Thanks for the LGTMs. I'll rebase and check this in.

[Randy Smith (Not in Mondays), 2011-08-19 21:44:14]

Yep--I believe this was originally intended as a proxy to confirm that we were
no longer observing the download manager in the destructor, and we're no longer
observing the download manager anywhere.  LGTM :-}.

[achuithb, 2011-08-19 21:51:55]

Thanks! Also take a look at http://codereview.chromium.org/7606024/ for the test
to cover this case.