Roll src/third_party/skia/ 56cf6dcb6..d1c94a415 (3 commits).
Roll src/third_party/skia/ 56cf6dcb6..d1c94a415 (3 commits).

https://chromium.googlesource.com/skia.git/+log/56cf6dcb6572..d1c94a41589c

$ git log 56cf6dcb6..d1c94a415 --date=short --no-merges --format='%ad %ae %s'
2015-11-30 halcanary CMake: generate skia.h and skia_{compile|link}_arguments.txt
2015-11-30 joshualitt Make onPrepareDraws const
2015-11-30 halcanary CMake: generate SkUserConfig.hh

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

Review URL: https://codereview.chromium.org/1485703004

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#362293}

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