Roll src/third_party/skia/ 40d8d6285..6f70d4371 (4 commits).
Roll src/third_party/skia/ 40d8d6285..6f70d4371 (4 commits).

https://chromium.googlesource.com/skia.git/+log/40d8d62854b7..6f70d43719d0

$ git log 40d8d6285..6f70d4371 --date=short --no-merges --format='%ad %ae %s'
2016-03-30 robertphillips Revert of Move SkGLContext and some GrGLInterface implementations to skgputest module (patchset #13 id:240001 of https://codereview.chromium.org/1815823002/ )
2016-03-30 bsalomon Move SkGLContext and some GrGLInterface implementations to skgputest module
2016-03-30 halcanary DM: allow vias to work with PDF backend
2016-03-30 djsollen Force include test to run on every compile.

CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
TBR=djsollen@google.com

Review URL: https://codereview.chromium.org/1843153002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#384065}

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