Roll src/third_party/angle ad5f71649e21..6e6539816196 (1 commits)

https://chromium.googlesource.com/angle/angle.git/+log/ad5f71649e21..6e6539816196

git log ad5f71649e21..6e6539816196 --date=short --no-merges --format='%ad %ae %s'
2019-10-10 lehoangq@gmail.com Added PVRTC compression extension needed for Metal on iOS.

Created with:
  gclient setdep -r src/third_party/angle@6e6539816196

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 geofflang@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=geofflang@google.com

Bug: None
Change-Id: I27b42746f5548f938aee6c3c2afa49d2c6c3fcc7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1853025Reviewed-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@{#704661}

DEPS

@@ -179,7 +179,7 @@ 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': 'ad5f71649e210069ab5427ddb46755358df220a1',
+  'angle_revision': '6e6539816196f8333dd6b3f7bf7405be178ba141',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling SwiftShader
   # and whatever else without interference from each other.