Roll src/third_party/skia 7da048b5e8f1..a9ac8a51fdb3 (4 commits)

https://skia.googlesource.com/skia.git/+log/7da048b5e8f1..a9ac8a51fdb3

git log 7da048b5e8f1..a9ac8a51fdb3 --date=short --no-merges --format='%ad %ae %s'
2019-10-30 herb@google.com Change uses of code to glyphID
2019-10-30 senorblanco@chromium.org Dawn: s/dawn::/wgpu::/g.
2019-10-30 senorblanco@chromium.org Dawn: roll to ToT.
2019-10-30 robertphillips@google.com Allocate all vertex data in one go w/in GrTextureOp

Created with:
  gclient setdep -r src/third_party/skia@a9ac8a51fdb3

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: None
Change-Id: Ibd8226be682c2f0bab64a7d2b1171a981e9038a4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1890832Reviewed-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@{#710867}

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': '7da048b5e8f17374bcd5baf48539eaa7ebe40e5c',
+  'skia_revision': 'a9ac8a51fdb30b488336d1e1541f33c44210f44c',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.