Roll src/third_party/skia 52a6a40535b0..b081bc4a3139 (4 commits) (#11267)

https://skia.googlesource.com/skia.git/+log/52a6a40535b0..b081bc4a3139

git log 52a6a40535b0..b081bc4a3139 --date=short --no-merges --format='%ad %ae %s'
2019-08-20 skia-recreate-skps@skia-swarming-bots.iam.gserviceaccount.com Update Go deps
2019-08-20 skia-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/externals/angle2 13cc0fce4340..6aca71d7d705 (5 commits)
2019-08-20 skia-autoroll@skia-public.iam.gserviceaccount.com Roll ../src 3b734c2675b5..8cd21345a0e8 (407 commits)
2019-08-20 skia-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/externals/swiftshader dadeb009a297..fd72dd0a439f (5 commits)

Created with:
  gclient setdep -r src/third_party/skia@b081bc4a3139

The AutoRoll server is located here: https://autoroll.skia.org/r/skia-flutter-autoroll

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.

Bug: None
TBR=egdaniel@google.com
https://dart.googlesource.com/external/github.com/flutter/engine/+/ca86f6d7e153a9d54d841c7c1fcb05ffe376dec4
diff --git a/commits.json b/commits.json
index d912d45..b1b1668 100644
--- a/commits.json
+++ b/commits.json
@@ -1,5 +1,5 @@
 {
-  "external/github.com/flutter/engine":"d212b9ab33a04a889a24952f76b3ba6b41e1df14",
+  "external/github.com/flutter/engine":"ca86f6d7e153a9d54d841c7c1fcb05ffe376dec4",
   "external/github.com/flutter/flutter":"e833a5820e798ad2e5920484b99a2d7bbb391460",
   "sdk":"3865187956cad51bc7065d30beb8ab89702b7953"
 }
\ No newline at end of file