Roll src/third_party/skia 538e358..f04f21a (2 commits)

https://skia.googlesource.com/skia.git/+log/538e358b0d82..f04f21a5c913

git log 538e358..f04f21a --date=short --first-parent --format='%ad %ae %s'
2020-03-23 skia-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/externals/swiftshader 1c9f24263e6c..22d73d15e778 (1 commits)
2020-03-23 skia-autoroll@skia-public.iam.gserviceaccount.com Roll ../src e0f773c501f9..be0a271f02d3 (446 commits)

Created with:
  gclient setdep -r src/third_party/skia@f04f21a5c913

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/skia-flutter-autoroll
Please CC robertphillips@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

Bug: None
Tbr: robertphillips@google.com

DEPS

@@ -26,7 +26,7 @@ vars = {
   'skia_git': 'https://skia.googlesource.com',
   # OCMock is for testing only so there is no google clone
   'ocmock_git': 'https://github.com/erikdoe/ocmock.git',
-  'skia_revision': '538e358b0d82bcf155943cfe34ef5f924b39ef7e',
+  'skia_revision': 'f04f21a5c91357352a41b55a357666702064a5f5',
 
   # When updating the Dart revision, ensure that all entries that are
   # dependencies of Dart are also updated to match the entries in the

ci/licenses_golden/licenses_skia

@@ -1,4 +1,4 @@
-Signature: a4d09cdc4a4c896c25db5bdb286e2805
+Signature: 8f53050411db4cb0f5aea62f7ebf48b7
 
 UNUSED LICENSES: