Add CTS tests for WebView#{init,shutdown}SafeBrowsing

This adds tests for the {init,shutdown}SafeBrowsing APIs:

 - initSafeBrowsing() always uses application Context
 - initSafeBrowsing() can be called with a null callback
 - initSafeBrowsing() calls its callback on the UI thread
 - shutdownSafeBrowsing() doesn't crash

These APIs mainly deal with GMSCore features, so it's very difficult to
reliably check their side effects. Instead, we just check that they
appear to behave sensibly.

Bug: 62192626
Test: run cts -m CtsWebkitTestCases -t android.webkit.cts.WebViewTest
Change-Id: If6596cfb170df4dc8550c43d24fe709457e6d3b8
1 file changed