Roll src/third_party/skia/ 6f70d4371..3243143f2 (5 commits).
Roll src/third_party/skia/ 6f70d4371..3243143f2 (5 commits).

https://chromium.googlesource.com/skia.git/+log/6f70d43719d0..3243143f25f4

$ git log 6f70d4371..3243143f2 --date=short --no-merges --format='%ad %ae %s'
2016-03-30 halcanary SkPDF:  SkTypeface::openStream could return nullptr
2016-03-30 robertphillips Update SkComposeImageFilter to sk_sp
2016-03-30 egdaniel Enable dual source blending for Vulkan
2016-03-30 msarett Correct png inverse gAMA when parsing color space
2016-03-30 brianosman Enable gpusrgb config on bots.

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

Review URL: https://codereview.chromium.org/1848503004

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#384104}

axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk