Fix WebViewUpdateServiceTest failures when using Thread without Looper.

Add some more methods to SystemInterface to avoid calling into the rest
of the framework from WebViewUpdateServiceTests.

Also convert WebViewUpdateServiceTest to use non-deprecated test
utilities.

Test: make sure tests in WebViewUpdateServiceTest pass.
Bug: 32364900
Change-Id: I8cf67568bb7e551e1c011028e0bb4e15c0e9f2bb
5 files changed