Remove accessor to the scalerContext on SkStrike

Also, the scaler is not implemented with multi-threaded code.
Protect it with the mutex.

Switch PathText viewer and benchmark over to using
SkBulkGlyphMetricsAndPaths.

Change-Id: I9a4be1afb22e5be68de0069de75eccc00ddb970c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/633177
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
4 files changed