Merge 139419 - fix crash when double-deleting a profile

Merge 139419 - fix crash when double-deleting a profile

this fixes both the UI (so it's impossible to trigger the crash) and skirts around the crash itself (which could potentially still be triggered via a UI race, i.e. if the user clicks fast enough).

BUG=129651
(maybe? not sure I understand that bug but this has a very similar stack signature)
TEST=create second profile. open delete dialog for that profile (don't delete yet). Go to profile 2 window, open settings. Open delete dialog for profile 2. Confirm delete of profile 2 on profile 2 window. Notice that the delete confirmation dialog in profile 1's window has now closed on its own.

Review URL: https://chromiumcodereview.appspot.com/10453020

TBR=estade@chromium.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=140461