Part 1) of cleaning up the code related to the shelf layout, specifically removing all instances of branching related to the 'alternate shelf layout' as this is now the only option.
Removed the about:flags entry relating to alternate shelf layout.

A patch will follow to simplify the remaining layout code as it is still a bit of a spaghetti like mess.

R=jamescook@chromium.org, skuhne@chromium.org
TBR=miket@chromium.org
BUG=338429

Review URL: https://codereview.chromium.org/140323010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254301 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 254301