The encoding
parameter is actually a misleading one.
When used in the context of the loadData
function, it's only used by the WebView to determine whether the data
is base-64 encoded or not. So it's value is meaningless unless you are passing base-64 encoded content, when it must be "base64"
(and should be lower case).
The case of the charset set in WebResourceResponse is case-insensitive.