Roll src/third_party/skia a9ac8a51fdb3..c7a8df8b1cdb (9 commits)

https://skia.googlesource.com/skia.git/+log/a9ac8a51fdb3..c7a8df8b1cdb

git log a9ac8a51fdb3..c7a8df8b1cdb --date=short --no-merges --format='%ad %ae %s'
2019-10-30 herb@google.com Swap SkPackedGlyphID bitfields around
2019-10-30 benjaminwagner@google.com [docs] Add skolo-builder to swarmingbots.md
2019-10-30 mtklein@google.com quick switch to disable SkVM JIT
2019-10-30 mtklein@google.com assume no color filters in SkVMBlitter
2019-10-30 mtklein@google.com clean up unorm8 helpers
2019-10-30 herb@google.com Faster remote glyph cache
2019-10-30 brianosman@google.com YUV Cleanup: Trim comments, derive Cr/Cb from Kr/Kb
2019-10-30 herb@google.com Use shifts for all fields in SkPackedGlyphID
2019-10-30 csmartdalton@google.com Rename sampleVariablesSupport() to sampleMaskSupport()

Created with:
  gclient setdep -r src/third_party/skia@c7a8df8b1cdb

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/skia-autoroll
Please CC jcgregorio@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

CQ_INCLUDE_TRYBOTS=luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux-blink-rel;luci.chromium.try:linux-chromeos-compile-dbg;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
TBR=jcgregorio@google.com

Bug: chromium:881505
Change-Id: Ibf34217fae3cca1d2c996982243b53552a5df0ef
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1890595Reviewed-by: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#710998}

DEPS

@@ -172,7 +172,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling Skia
   # and whatever else without interference from each other.
-  'skia_revision': 'a9ac8a51fdb30b488336d1e1541f33c44210f44c',
+  'skia_revision': 'c7a8df8b1cdbc63a1ac2ceceb91f59db5a963272',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.