SoftwareOutputDevice implementation using an OZONE software renderer as the backend.

SOD's expectation is that Ozone provides a SkCanvas as the accelerated widget.

BUG=

Review URL: https://codereview.chromium.org/23862004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230488 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 230488