Add WebView#{init,shutdown}SafeBrowsing APIs

This adds the APIs for the WebView#initSafeBrowsing and
WebView#shutdownSafeBrowsing static methods.

Implementation for these APIs landed in 60.0.3112.0

Also, this fixes an already-existing error with import order (failed
Checkstyle hook). No actual change to imports.

BUG: 62192626
Test: manual - built a custom app which calls methods via reflection
Change-Id: I763349182443dc20cff1e7f08475290fac65c233