Once we move the assist code out of Aw to content and combine the path for webview and chrome, this test became untrivial to test because ViewStructure does not lend itself to testing (a large abstract class):

 @Feature({"AndroidWebView"})
    @SmallTest
    public void testRequestAccessibilitySnapshotAboutBlank() throws Throwable {
        
        AccessibilitySnapshotNode root = receiveAccessibilitySnapshot(null, null);
        assertEquals(null, root);
    }

 both this and some cases in Content that would benefit from mocking viewstructure and testing.