Various past bugs have shown that developers often call loadUrl(url) in shouldOverrideUrlLoading, and then return true, instead of simply returning false. This causes various unexpected effects since it restarts the navigation instead of continuing it, and has tickled bugs in WebView before.

We could probably detect the most basic cases of this pretty easily and tell them this is wrong: just stash the URL somewhere before calling shouldOverrideUrlLoading and then if we receive a loadUrl call for the exact same URL (without any additional headers, which is a semi-valid use case), Log.w() a message telling them this is unnecessary.