Add accessors for WebViewFactory.UseExperimentalWebView

In preperation for flag-flip, have Settings app access the current
state via methods that are neutral to the on/off state.
Also setup the property to change name when enabled by default, to reset
any user changes to this setting.

Change-Id: I55017bcd89573c1ecac7de8913264d9cf66fdcd9
1 file changed