Roll src/third_party/skia cb6b4bde0c2e..21a7be0741ac (3 commits) (#7216)

https://skia.googlesource.com/skia.git/+log/cb6b4bde0c2e..21a7be0741ac


Created with:
  gclient setdep -r src/third_party/skia@21a7be0741ac

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.

DEPS

@@ -23,7 +23,7 @@ vars = {
   'fuchsia_git': 'https://fuchsia.googlesource.com',
   'github_git': 'https://github.com',
   'skia_git': 'https://skia.googlesource.com',
-  'skia_revision': 'cb6b4bde0c2e02bfdbd63883cb08995a6fe823d4',
+  'skia_revision': '21a7be0741ac3db30dcae0ccfe40ff55920b158f',
 
   # 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

-Signature: 029028f23d38d6a4a619879f7f12bde4
+Signature: d30056bf8c94442becdd1fc941fed8cd
 
 UNUSED LICENSES:
 
@@ -1615,6 +1615,8 @@ FILE: ../../../third_party/skia/src/gpu/text/GrSDFMaskFilter.cpp
 FILE: ../../../third_party/skia/src/gpu/text/GrSDFMaskFilter.h
 FILE: ../../../third_party/skia/src/gpu/vk/GrVkAMDMemoryAllocator.cpp
 FILE: ../../../third_party/skia/src/gpu/vk/GrVkAMDMemoryAllocator.h
+FILE: ../../../third_party/skia/src/gpu/vk/GrVkCommandPool.cpp
+FILE: ../../../third_party/skia/src/gpu/vk/GrVkCommandPool.h
 FILE: ../../../third_party/skia/src/gpu/vk/GrVkImageLayout.h
 FILE: ../../../third_party/skia/src/gpu/vk/GrVkPipelineLayout.cpp
 FILE: ../../../third_party/skia/src/gpu/vk/GrVkPipelineLayout.h