Have SkScalerCache return memory used

The SkScalerCache now returns the amount of memory allocated
for each operation. The SkStrikeCache can now start using this
information to track cache size.

Change-Id: Ie0e8138015c6692257126a7bb02a3773b10a7b0a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/271476
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Herb Derby <herb@google.com>
4 files changed