Roll src/third_party/skia 9a049e6ce39d..63c4d3596915 (8 commits) (#7909)

https://skia.googlesource.com/skia.git/%2Blog/9a049e6ce39d..63c4d3596915

git log 9a049e6ce39d9a7c0270b5f52ca21035e71032ef..63c4d3596915ca38eb47266a98c6f5d99399b52e --date=short --no-merges --format=%ad %ae %s
2019-02-21 mtklein@google.com Revert "remove linear sRGB singleton"
2019-02-21 reed@google.com fix mac format for gm
2019-02-21 skia-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/externals/swiftshader 0eee33250ebb..3fc635ac4a7f (1 commits)
2019-02-21 scroggo@google.com Remove SK_SUPPORT_LEGACY_ANDROID_CODEC_COLORSPACE
2019-02-21 recipe-roller@chromium.org Roll recipe dependencies (trivial).
2019-02-21 egdaniel@google.com Return correct GrBackendFormat when ycbcr conversion is valid.
2019-02-21 reed@google.com add gm for aa gamma
2019-02-13 mtklein@google.com remove linear sRGB singleton

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 (jvanverth@google.com), 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': '9a049e6ce39d9a7c0270b5f52ca21035e71032ef',
+  'skia_revision': '63c4d3596915ca38eb47266a98c6f5d99399b52e',
 
   # 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: 6d414f70a2508ca7c53b28f953a9811a
+Signature: 4adbd887c4d5bb308d83699e0800a51a
 
 UNUSED LICENSES: