Move GrGLInterface function ptr setup into a common function for all OpenGL GrGLInterface factories (but not GLES yet).

R=robertphillips@google.com

Author: bsalomon@google.com

Review URL: https://codereview.chromium.org/254713006

git-svn-id: http://skia.googlecode.com/svn/trunk@14444 2bbb7eff-a529-9590-31e7-b0007b416f81
8 files changed