Remove unused Device Orientation code from content/renderer.

Remove old Device Orientation code, because new implementation is in
place see crbug.com/261165. New content-side Device Orientation now
lives in content/renderer/device_orientation/.

The corresponding clean-up in Blink:
https://codereview.chromium.org/25295002/

BUG=261165

Review URL: https://codereview.chromium.org/25253003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226211 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226211