GitLab

Currently contains the title and the account chooser.  In the next CL, I'm
planning to move notifications into the header as well.

BUG=315977
TEST=none
R=groby@chromium.org

Review URL: https://codereview.chromium.org/77283002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236997 0039d316-1c4b-4281-b951-d872f2087c98