This is a tracking bug for system health news and media browsing benchmarks.

Benchmark CLs:
1) News browsing: https://codereview.chromium.org/2118293002/
2) Media browsing: https://codereview.chromium.org/2124823002/

TODO items:
1) Sync websites in load:news and browse:news. Make sure that (browse:news) is a subset of (load:news).
   a) Add qq.com to browse:news.
   b) Add nytimes, hackernews, washingtonpost to load:news.
   c) Sync urls of all websites in load:news and browser:news.
2) Land browse:news.
3) Rebase browse:media on top of browse:news.
4) Sync browse:media with load:media (?)
5) Land browse:media
6) Add browse:news and media:news stories to system health benchmark.