Support reading pixels from HW-decoded video textures into canvas/webgl.

BUG=153094


Review URL: https://chromiumcodereview.appspot.com/11016006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@159571 0039d316-1c4b-4281-b951-d872f2087c98
8 files changed