[OriginChip] Don't show Chrome icon for about: scheme pages.

Also, remove a DCHECK condition that's no longer valid after https://codereview.chromium.org/101513008.

BUG=331908

Review URL: https://codereview.chromium.org/139313004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246428 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246428
Remove robot image that was never used.

BUG=None
NOTRY=true

Review URL: https://codereview.chromium.org/144003011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246429 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246429