shouldInterceptRequest on Android 4.4 KitKat

I have an App that uses custom schemes in Android WebViewClient's `shouldInterceptRequest(WebView view, String url)` and `shouldOverrideUrlLoading(WebView view, String url)` to intercept requests in a web application and use a native library to fetch resources from elsewhere in `shouldInterceptRequest`. This has worked fine up until Android 4.4 KitKat, where Google has made some crucial changes to the webView component. http://developer.android.com/guide/webapps/migrating.html#URLs Now the url received in `shouldOverrideUrlLoading` suddenly gets invalid, looking like this; custom-scheme:////my.pathname.com/. First I suspected the extra slashes were because Android did not think the url were valid RFC3986, but in a series of resource fetches (css, js, images), the url starts off correct and suddenly changes to the invalid format. The webView in Android 4.3 kept the url correctly as custom-scheme://my.pathname.com/. It seems like the base url suddenly changes to '/' instead of 'my.pathname.com'. Then my attention changed to the fact that the webView 4.4 migration guide talks about: If you call methods on WebView from any thread other than your app's UI thread, it can cause unexpected results. http://developer.android.com/guide/webapps/migrating.html#Threads This also might be what I am experiencing, but I have not yet come up with a solution where I can use `runOnUiThread()` to fetch data with the native api and return it to the webView inside `shouldInterceptRequest`. Has anyone experienced something similar? Here is a simplified version of my `shouldInterceptRequest` code: ``` @Override public WebResourceResponse shouldInterceptRequest(WebView view, String url) { if (urlStartsWithKnownPrefix(url)) { UrlFetchResult fetchRes = api.fetchUrl(url); String charset = "utf-8"; String mime = fetchRes.getMimetype(); WebResourceResponse res = new WebResourceResponse(mime, charset, new ByteArrayInputStream(fetchRes.getResult())); return res; } return null; } ```