cleanup: Replace usage of chrome::AddBlankTabAt with chrome::AddTabAt().

BUG=319011
[email protected]

Review URL: https://codereview.chromium.org/73503007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235542 0039d316-1c4b-4281-b951-d872f2087c98
32 files changed