move GrTextBlobCache to GrContextThreadSafeProxy

ninja -C out/Release -j 800 skpbench && ./out/Release/skpbench \
--config gl --ddl --src skps/desk_nytimes.skp \
--ddlTilingWidthHeight 3 --gpuThreads 0 \
--pr ~small ~nvpr --cachePathMasks false --comparableDDL
Reports:
with out cl:
1.949     1.842     3.979     1.802      29%       99         50  cpu    ms      gl        desk_nytimes.skp

this cl:
1.476     1.388     3.342     1.365    34.2%       99         50  cpu    ms      gl        desk_nytimes.skp

Non-ddl perf:
./out/Release/skpbench --config gl --ddl --src skps/desk_nytimes.skp \
--ddlTilingWidthHeight 3 --gpuThreads 0 --pr ~small ~nvpr \
--cachePathMasks false --comparableSKP

 1.368      1.31     2.276     1.273    15.3%       99         50  cpu    ms      gl        desk_nytimes.skp

Change-Id: I879f779e34b5c717ab5602f23374aedaff56f96b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/299197
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Herb Derby <herb@google.com>
5 files changed