Revert "App compat: Temporarily rename CopyOnWriteArrayList.array -> elements"

This change was made in the O timeframe to fix an app compat issue for
apps which were accessing this field via reflection, with a plan to
keep it around for one release. Developers were notified in December
2016. Also, we now have hidden API protection. This should therefore
be safe to revert for the next release.

This reverts commit 3e090b8032714c0912697b678b8ab9d26bc1739b.

Bug: 112520217
Bug: 34099995
Test: `make core-all`
Change-Id: Id69a1c790164661505778c380ab99d87a9a7aa6b
1 file changed