GitLab

- Don't look for common title prefixes between pages from different hosts.

- Bring down the minimal width of a tab title area from 10 to 6 chars.

- Don't elide last 4 chars of the common prefix, and also don't elide if there is less than 7 common characters.

BUG=None
TEST=Try it!
Review URL: http://codereview.chromium.org/6783015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@80492 0039d316-1c4b-4281-b951-d872f2087c98