Consider redirects to data:// urls as cancelling a request and don't report conflicts

If an extension A tries to redirect a request to http://foo and an extension B tries to redirect a request to data://..., we consider the redirect of extension B as an attempt to cancel the request. As cancelling a request is considered to take precedence over redirects, this does not generate a conflict message any more.


BUG=106431
TEST=no


Review URL: http://codereview.chromium.org/8802017

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@113068 0039d316-1c4b-4281-b951-d872f2087c98