Roll src/third_party/angle 3a8b8908605b..6b652b335259 (3 commits)

https://chromium.googlesource.com/angle/angle.git/+log/3a8b8908605b..6b652b335259

git log 3a8b8908605b..6b652b335259 --date=short --no-merges --format='%ad %ae %s'
2019-10-24 ianelliott@google.com Vulkan: Update expectations for SwiftShader sRGB fix
2019-10-24 jmadill@chromium.org Vulkan: Enable multithreading tests.
2019-10-24 jmadill@chromium.org GN: Fix one missing check for 'angle_has_build'.

Created with:
  gclient setdep -r src/third_party/angle@6b652b335259

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/angle-chromium-autoroll
Please CC jonahr@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_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
TBR=jonahr@google.com

Bug: None
Change-Id: I50c0eb41c0d2d6a598f80a45c341a97cdd2fe3d0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1879701Reviewed-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@{#709193}

DEPS

@@ -183,7 +183,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling ANGLE
   # and whatever else without interference from each other.
-  'angle_revision': '3a8b8908605bbb8da453cf5cee466922736d70f2',
+  'angle_revision': '6b652b335259295d90702fff9f3b34988eef36f7',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling SwiftShader
   # and whatever else without interference from each other.