[skia-sync] Merge upstream chrome/m148

[mattleibow]

Automated upstream merge of chrome/m148.

Summary

Release-line bug-fix sync onto release/4.148.x. Pulls 2 new upstream commits from google/skia chrome/m148 into mono/skia release/4.148.x via the skia-sync/release-4.148.x branch.

This is not a milestone bump — CURRENT == TARGET == 148. No SkiaSharp version/soname/nuget changes; the parent-repo companion PR only bumps the submodule pointer and the two cgmanifest.json SHAs.

Upstream merge

Field	Value
Upstream ref	chrome/m148 (google/skia)
Old upstream HEAD	54851b68b7a1d49bc4b4361f12786a7d7ad91fff
New upstream HEAD	46f2e16555cac1211f4087cf24728fd741ac6495
Merge-base	54851b68b7a1d49bc4b4361f12786a7d7ad91fff
New upstream commits	2
Merge commit on this branch	6d45d9aed12bacb599261ccebcf4a9764b0467ea

Upstream commits pulled in

SHA	Subject	Files
46f2e16555	[m148] Resolved a Data Race on fStream in SkTypeface_Mac	src/ports/SkTypeface_mac_ct.{cpp,h}
3a90f6662a	[graphite] Use stable collection for static bindings	src/gpu/graphite/dawn/DawnGraphicsPipeline.cpp

Both are cherry-picked bug-fixes (already on chrome/m148 upstream). The first is a macOS-only thread-safety fix in CoreText typeface caching (gTFCache); the second is a Graphite/Dawn-only buffer-stability fix. SkiaSharp ships Ganesh (not Graphite), so the Graphite change is benign noise. The macOS typeface fix is the genuinely valuable bug-fix for SkiaSharp users on macOS — it eliminates a data race where onOpenStream and onOpenExistingStream could race on fStream from different threads.

Conflicts resolved

None. git merge --no-commit completed with "Automatic merge went well"; git diff --check reports zero conflict markers. The 2 upstream commits touch 3 files only, all outside our fork patches.

Fork-patch audit (mandatory snapshot before merging):

$ MB=$(git merge-base origin/release/4.148.x upstream/chrome/m148)
$ git log --oneline "$MB..origin/release/4.148.x" | wc -l
963   # snapshot saved in workflow artifacts as fork-patches-before.txt

No fork patch touches src/ports/SkTypeface_mac_ct.{cpp,h} or src/gpu/graphite/dawn/DawnGraphicsPipeline.cpp, so nothing needed to be re-applied or classified as upstreamed.

C API impact

None. Neither upstream commit touches:

• src/c/** or include/c/** (SkiaSharp C shim)
• src/xamarin/** or include/xamarin/** (SkiaSharp Xamarin shim)
• BUILD.gn, DEPS, modules/skcms/version.sha1
• Any public header pulled in by our C API

The binding generator was re-run in the parent repo and reports No changes to bindings (C API signatures unchanged) and No new functions found. SK_C_INCREMENT stays at 0.

Source-file verification

$ git diff $(git merge-base origin/release/4.148.x upstream/chrome/m148)..upstream/chrome/m148 \
    --diff-filter=AD --name-only -- src/ include/
(empty — no added or deleted source files)

No BUILD.gn adjustments required.

Items needing human attention

• None. Pure bug-fix sync, clean merge, no C API impact, no binding deltas, all tests pass in the companion PR.
• Linux x64 was the build platform used in CI here. The macOS data-race fix (SkTypeface_mac_ct.cpp) is not exercised by the Linux x64 native build or test suite; the macOS native build will pick it up automatically on the release/4.148.x macOS pipeline once both PRs land.

Companion PR

Parent repo: mono/SkiaSharp PR on branch skia-sync/release-4.148.x targeting release/4.148.x. The parent PR bumps the submodule pointer to the merge commit of this PR and updates the two cgmanifest.json SHAs (mono/skia commitHash and Skia core upstream_merge_commit).

Created by skia-upstream-sync.