[SiteChip] Remove 50% width cap for site chip

R=pkasting@chromium.org
BUG=331373

Review URL: https://codereview.chromium.org/141333004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249497 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249497