A recent change to the way we close tabs (http://codereview.chromium.org/235050) causes Browser::CanCloseContentsAt() to be called several times for the same tab. This was triggering a DCHECK in the "download in progress" warning.
A recent change to the way we close tabs (http://codereview.chromium.org/235050)
causes Browser::CanCloseContentsAt() to be called several times for the same tab.
This was triggering a DCHECK in the "download in progress" warning.

BUG=24974
TEST=See bug. Test thoroughly the "dowload in progress" warning: start a big
     download, then close Chrome (by closing all tabs, by using the top window
     close button). Make sure both behaviors (continue/abort closing) work as 
     expected.

Review URL: http://codereview.chromium.org/273076

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@29289 0039d316-1c4b-4281-b951-d872f2087c98

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