[androidkit] Add linear gradient

Change-Id: Ie08dcde421bb4f67b8467361bda563d5a65ddbd2
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/416777
Commit-Queue: Florin Malita <fmalita@google.com>
Reviewed-by: Jorge Betancourt <jmbetancourt@google.com>
6 files changed