[canvaskit] perform audio asset lookup by layer id

Change-Id: Iac56d11a76be8d90df1159631a02f1713ece1bd8
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/368938
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Jorge Betancourt <jmbetancourt@google.com>
3 files changed