This change also updates the WidevineEncryptionKeySource to be able to support
KeyRotation enabled and disabled requests simultaneously.
Change-Id: I5178cafc0dbabbb64ac9af9969d3bf7d8117a4dd
The key production thread was started in constructor. The default http
fetcher might have already been used to fetch keys before it is modified
by set_http_fetcher. This could lead to flaky unittest.
Change-Id: I977b6450862d87ffeb5cb219bcd46b33d877e550