Revert 265044 "Don't leave aborted URLs in the omnibox unless we..."

Revert 265044 "Don't leave aborted URLs in the omnibox unless we..."

This appears to be breaking prerender tests on some Mac and Linux builders.

e.g.

Mac:
http://build.chromium.org/p/chromium.mac/builders/Mac%2010.7%20Tests%20%28dbg%29%284%29/builds/22698/steps/browser_tests/logs/PrerenderDoublePendingSwap
http://build.chromium.org/p/chromium.mac/builders/Mac%2010.6%20Tests%20%28dbg%29%284%29/builds/40342/steps/browser_tests/logs/PrerenderPageNewTab

Linux ASan:
http://build.chromium.org/p/chromium.memory/builders/Linux%20ASan%20Tests%20%28sandboxed%29/builds/971/steps/browser_tests/logs/PrerenderPageNewTab

> Don't leave aborted URLs in the omnibox unless we're on the NTP.
>
> BUG=355537
> TEST=See bug for repro steps.
>
> Review URL: https://codereview.chromium.org/232463007

TBR=creis@chromium.org

Review URL: https://codereview.chromium.org/244693007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@265069 0039d316-1c4b-4281-b951-d872f2087c98