Roll src/third_party/skia f686040..8561fc2 (7 commits) (flutter#17592)

https://skia.googlesource.com/skia.git/+log/f6860405e1bf..8561fc23c927

git log f686040..8561fc2 --date=short --first-parent --format='%ad %ae %s'
2020-04-08 [email protected] Update gpu flush semaphore contract.
2020-04-08 [email protected] Dawn: staging manager rewrite.
2020-04-08 [email protected] [SVG] Fix spec links
2020-04-08 [email protected] stifle leaks in terminator_CreateDevice()
2020-04-08 [email protected] get skvm/llvm building again
2020-04-08 [email protected] narrow use of fast_unwind_on_malloc=0
2020-04-08 [email protected] shard ASAN bonusconfigs bot

Created with:
  gclient setdep -r src/third_party/skia@8561fc23c927

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 [email protected] 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: [email protected]

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': 'f6860405e1bf4603cb393c1818454dc3f893a07a',
+  'skia_revision': '8561fc23c927525d370b62b73b431d51ed574935',
 
   # 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: 91431c0474883af27c1e7c0e3dee8955
+Signature: cf555339cd3f5572c9e165ed69278b0c
 
 UNUSED LICENSES:
 
@@ -1117,6 +1117,7 @@ FILE: ../../../third_party/skia/infra/bots/recipe_modules/flavor/examples/full.e
 FILE: ../../../third_party/skia/infra/bots/recipe_modules/flavor/examples/full.expected/Test-Debian10-Clang-GCE-CPU-AVX2-x86_64-Release-All-Lottie.json
 FILE: ../../../third_party/skia/infra/bots/recipe_modules/flavor/examples/full.expected/Test-Debian10-Clang-GCE-CPU-AVX2-x86_64-Release-All-TSAN.json
 FILE: ../../../third_party/skia/infra/bots/recipe_modules/flavor/examples/full.expected/Test-Debian10-Clang-GCE-GPU-SwiftShader-x86_64-Debug-All-SwiftShader.json
+FILE: ../../../third_party/skia/infra/bots/recipe_modules/flavor/examples/full.expected/Test-Debian10-Clang-NUC7i5BNK-GPU-IntelIris640-x86_64-Debug-All-ASAN_Vulkan.json
 FILE: ../../../third_party/skia/infra/bots/recipe_modules/flavor/examples/full.expected/Test-Debian10-Clang-NUC7i5BNK-GPU-IntelIris640-x86_64-Debug-All-OpenCL.json
 FILE: ../../../third_party/skia/infra/bots/recipe_modules/flavor/examples/full.expected/Test-Debian10-Clang-NUC7i5BNK-GPU-IntelIris640-x86_64-Debug-All-Vulkan.json
 FILE: ../../../third_party/skia/infra/bots/recipe_modules/flavor/examples/full.expected/Test-Debian10-GCC-GCE-CPU-AVX2-x86-Debug-All-Docker.json
@@ -3108,8 +3109,6 @@ FILE: ../../../third_party/skia/src/gpu/dawn/GrDawnRenderTarget.cpp
 FILE: ../../../third_party/skia/src/gpu/dawn/GrDawnRenderTarget.h
 FILE: ../../../third_party/skia/src/gpu/dawn/GrDawnRingBuffer.cpp
 FILE: ../../../third_party/skia/src/gpu/dawn/GrDawnRingBuffer.h
-FILE: ../../../third_party/skia/src/gpu/dawn/GrDawnStagingManager.cpp
-FILE: ../../../third_party/skia/src/gpu/dawn/GrDawnStagingManager.h
 FILE: ../../../third_party/skia/src/gpu/dawn/GrDawnStencilAttachment.cpp
 FILE: ../../../third_party/skia/src/gpu/dawn/GrDawnStencilAttachment.h
 FILE: ../../../third_party/skia/src/gpu/dawn/GrDawnTexture.cpp
@@ -5630,7 +5629,11 @@ FILE: ../../../third_party/skia/src/core/SkVerticesPriv.h
 FILE: ../../../third_party/skia/src/gpu/GrDynamicAtlas.cpp
 FILE: ../../../third_party/skia/src/gpu/GrDynamicAtlas.h
 FILE: ../../../third_party/skia/src/gpu/GrEagerVertexAllocator.h
+FILE: ../../../third_party/skia/src/gpu/GrStagingBuffer.cpp
+FILE: ../../../third_party/skia/src/gpu/GrStagingBuffer.h
 FILE: ../../../third_party/skia/src/gpu/ccpr/GrAutoMapVertexBuffer.h
+FILE: ../../../third_party/skia/src/gpu/dawn/GrDawnStagingBuffer.cpp
+FILE: ../../../third_party/skia/src/gpu/dawn/GrDawnStagingBuffer.h
 FILE: ../../../third_party/skia/src/gpu/ops/GrSimpleMeshDrawOpHelperWithStencil.cpp
 FILE: ../../../third_party/skia/src/gpu/ops/GrSimpleMeshDrawOpHelperWithStencil.h
 FILE: ../../../third_party/skia/src/gpu/tessellate/GrDrawAtlasPathOp.cpp