Reland: Android: Replace ConcurrentHashMap usage with manual lock.

ConcurrentHashMap has a bug on L.
* Also adds a checkstyle check to prevent future uses.
* Also adds @AnyThread / @MainThread to all public methods

Reason for reland:
 * Now synchronizing map iterators

Bug: 905903
Change-Id: Id7788a4707329a5e441cc010e1fb297668510aef
Reviewed-by: Tibor Goldschwendt <>
Commit-Queue: agrieve <>
Cr-Original-Commit-Position: refs/heads/master@{#622699}
Cr-Mirrored-Commit: b7225829975f5a97b986f51cd4c2df74bd237271
1 file changed