Make SkRemoteGlyphCache obey the prepareForDrawing contract

Change-Id: I3f781b8d72f460edb73c5b3d446676db19a4a935
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/215090
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: Khushal Sagar <khushalsagar@chromium.org>
2 files changed