Roll external/skia f975b3eb6..2e5eaf022 (2 commits)

https://skia.googlesource.com/skia.git/+log/f975b3eb6..2e5eaf022

2017-06-22 jvanverth@google.com Revert "Revert "Clean up onTransferPixels""
2017-06-22 robertphillips@google.com Roll ANGLE

Test: Presubmit checks will test this change.
Change-Id: Id4d7498c1450d9ff5df6b117cd62c45bbb44c224