[PM] Lift NodeAttachedData to public interface.

This adds opaque ToNodeBase functionality to public node types allowing
the NodeAttachedData implementation to avoid specialization for each
known public node type.

BUG=958115

Change-Id: Ib19c07319d43205560fd4086a919abee30cab5d6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1597694
Commit-Queue: Chris Hamilton <[email protected]>
Reviewed-by: Sigurður Ásgeirsson <[email protected]>
Cr-Commit-Position: refs/heads/master@{#657740}
20 files changed