Roll Skia from a60a52a11763 to 321d7750aa07 (2 revisions) (flutter/engine#55290)

https://skia.googlesource.com/skia.git/+log/a60a52a11763..321d7750aa07

2024-09-18 skia-autoroll@skia-public.iam.gserviceaccount.com Manual roll Dawn from 31cb19d6c599 to d3e90db0af37 (16 revisions)
2024-09-18 nicolettep@google.com [graphite] Immutable sampler data appending + processing fixes

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 brianosman@google.com,chinmaygarde@google.com,jmbetancourt@google.com,rmistry@google.com on the revert to ensure that a human
is aware of the problem.

To file a bug in Skia: https://bugs.chromium.org/p/skia/issues/entry
To file a bug in Flutter: https://github.com/flutter/flutter/issues/new/choose

To report a problem with the AutoRoller itself, please file a bug:
https://issues.skia.org/issues/new?component=1389291&template=1850622

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

DEPS

@@ -14,7 +14,7 @@ vars = {
   'flutter_git': 'https://flutter.googlesource.com',
   'skia_git': 'https://skia.googlesource.com',
   'llvm_git': 'https://llvm.googlesource.com',
-  'skia_revision': 'a60a52a117638ed8e67cdf6624a312c3deb6ea65',
+  'skia_revision': '321d7750aa075f0d46dff07f8668c7dd815efc04',
 
   # WARNING: DO NOT EDIT canvaskit_cipd_instance MANUALLY
   # See `lib/web_ui/README.md` for how to roll CanvasKit to a new version.

engine/src/flutter/ci/licenses_golden/licenses_skia

@@ -1,4 +1,4 @@
-Signature: b55ebed547e35aad5f68289faddba529
+Signature: 706160cdd438d2776c7b469e906b892a
 
 ====================================================================================================
 LIBRARY: etc1