Roll src/third_party/skia a8352ccaae37..e6d31bd0894c (3 commits)

https://skia.googlesource.com/skia.git/+log/a8352ccaae37..e6d31bd0894c

git log a8352ccaae37..e6d31bd0894c --date=short --first-parent --format='%ad %ae %s'
2019-12-19 benjaminwagner@google.com [infra] Use unbuffered I/O for run_recipe
2019-12-19 reed@google.com extend imageshader updater to handle perspective
2019-12-19 jvanverth@google.com Tweak smallpaths so new paths will show up in GM.

Created with:
  gclient setdep -r src/third_party/skia@e6d31bd0894c

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 borenet@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
Bug: None
Tbr: borenet@google.com
Change-Id: Ic86dc15fecf43e9f8058c4aae9cdb77645ba85d9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1976663Reviewed-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@{#726524}

DEPS

@@ -175,7 +175,7 @@ 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': 'a8352ccaae3704526d99b6cff82a4f7c294f8f68',
+  'skia_revision': 'e6d31bd0894c49e9c2f23b2c5160452030e6b2e2',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.