Roll src/third_party/skia ac856c9:b6bf367

Roll src/third_party/skia ac856c9:b6bf367

Summary of changes available at:
https://chromium.googlesource.com/skia/+log/ac856c9..b6bf367

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

Commits in this roll:
b6bf367 rmistry@google.com Revert of By default purge resources that haven't been used for 64 flushes (patchset #2 id:20001 of https://codereview.chromium.org/1316233003/ )
38f1f6f mdempsky@chromium.org Remove overly complicated GR_CREATE_STATIC_PROCESSOR macro
6904d1d mtklein@chromium.org Add a note about (x*y+255)/256.
e01008f mtklein@chromium.org Add trace event to SkPicture analysis.
885bf09 hendrikw@chromium.org skia: add ability to load command_buffer_gles2
33c594c ssid@chromium.org [tracing] Add support for skia caches to dump memory stats
8504717 bsalomon@google.com By default purge resources that haven't been used for 64 flushes
aaf951d halcanary@google.com nullptr isn't an int; this is what we want
96fcdcc halcanary@google.com Style Change: NULL->nullptr DOCS_PREVIEW= https://skia.org/?cl=1316233002
435af2f mtklein@chromium.org SkColorCubeFilter_opts: start with a statically-initializable zero.
fe495f0 chinmaygarde@google.com Fix assertion about GPU memory size when the target is not FBO 0

Review URL: https://codereview.chromium.org/1321693006

Cr-Commit-Position: refs/heads/master@{#346027}