Fix masks when scaling is in the tree

Because the render surface is sized according to the screen-space footprint,
there is a scaling factor introduced between the RS and the owning layer, that
was not taken into account for masks. This fixes that.

BUG=163045


Review URL: https://chromiumcodereview.appspot.com/11883027

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@176850 0039d316-1c4b-4281-b951-d872f2087c98
2 files changed