pass SkImageInfo to pixelref constructor

BUG=
R=fmalita@chromium.org, scroggo@google.com

Review URL: https://codereview.chromium.org/113043002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240165 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 240165