There are large chunks of UMA tracking code in CustomTabActivity: see e.g. onResumeWithNative() and recordClientPackageName(). Extract them into a separate class.

See CustomTabActivityUmaTracker.java in https://crrev.com/1371805 for a rough idea how this class may look like.

This is a part of CustomTabActivity refactoring plan described in
https://docs.google.com/document/d/1E9u-9eSFjLwVnUUIekhurmKk-8vsSDxek7cZiFd6ToY