Merge PR #540: Complete Material 3 migration

Changes from PR #540 are already present in master as commits
2e4e0c5, 8a33000, 081d4b5 -- patch-identical to the PR branch
commits d2d5606, ee0f0d6, ab3de53 (they were rebased and
landed directly), plus follow-up fix 7e6bccb.

Recording this merge so GitHub auto-closes PR #540 as merged.

Author: kasnder