Roll src/third_party/skia 4ef1ca1d089e..a8352ccaae37 (2 commits)

https://skia.googlesource.com/skia.git/+log/4ef1ca1d089e..a8352ccaae37

git log 4ef1ca1d089e..a8352ccaae37 --date=short --first-parent --format='%ad %ae %s'
2019-12-19 nifong@google.com Write a debugger user guide.
2019-12-19 robertphillips@google.com Add test for the GrContext::createCompressedBackendTexture API

Created with:
  gclient setdep -r src/third_party/skia@a8352ccaae37

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: I3a3b9e4a2ab3718f6ece8a630a62fdcfd8e32d42
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1976740Reviewed-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@{#726471}

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': '4ef1ca1d089e909c8d62a36ea6f604696e784094',
+  'skia_revision': 'a8352ccaae3704526d99b6cff82a4f7c294f8f68',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.