GitLab

This CL also renames the class name to AthenaStartPageView
and I am expecting to use the same view to CENTERED state,
so that we can achieve the smooth state transition meanwhile.

BUG=401570
R=sadrul@chromium.org
TEST=manually

Review URL: https://codereview.chromium.org/473623002

Cr-Commit-Position: refs/heads/master@{#289690}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@289690 0039d316-1c4b-4281-b951-d872f2087c98