* Make final where possible
* Remove unused casts, imports, methods, enums and constructors
* Add null checks
Change-Id: Idd1a16426dd1928e2ed9922f5a35ba32ce4f808b
The version of OkHttp used in AOSP doesn't handle dynamic table size
updates [1] properly [2]. Instead of fixing OkHttp or importing a
prebuilt updated version, implement a new download client only using
HttpURLConnection, which seems to work properly.
[1] https://tools.ietf.org/html/rfc7541#section-6.3
[2] https://trac.nginx.org/nginx/ticket/1397
Change-Id: I3eedf7326f2017812c4a12d41f9ea028d255f7a8
