Fix omnibox update bug.
Fix omnibox update bug.

When tab-switching happens, the state of the tab is stored so that it can be restored later. However, when a background tab is being closed, it doesn't cause a tab-switch, and trying to save the state causes problems in some cases (e.g. 61588). So do not save state of a background tab.

BUG=61588
TEST=see bug

Review URL: http://codereview.chromium.org/5075001

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@66445 0039d316-1c4b-4281-b951-d872f2087c98

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