attach a download listener to the web view and change the url as follows..
“https://docs.google.com/gview?embedded=true&url=https://www.example.com/xxxxxyyyyyxz.pdf”
example
https://docs.google.com/gview?embedded=true&url=https://www.adobe.com/support/products/enterprise/knowledgecenter/media/c4611_sample_explain.pdf
it’s a link used to open pdf without downloading it…
I hope it solves your problem..