Change the wording of the warning on the extension install

dialog from "needs access to" to "can access" per discusison
on chromium-discuss.

Review URL: http://codereview.chromium.org/1806002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@45826 0039d316-1c4b-4281-b951-d872f2087c98