Calculate rough approximations for nvpr path sizes

Calculates a rough approximation of the actual value for gpuMemorySize
in GrGLPath and GrGLPathRange, instead of assuming every path is the
same fixed size.

BUG=skia:
R=bsalomon@google.com, markkilgard@gmail.com

Author: cdalton@nvidia.com

Review URL: https://codereview.chromium.org/442603002
4 files changed