Remove obsolete --low-resolution-contents-scale-factor command line switch

This switch was used to control the scale of low resolution tiles on
specific Android devices, but since we do not do that anymore, we can
remove this switch.

BUG=177027

Review URL: https://codereview.chromium.org/95623002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237927 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237927