Android : Show a pdf in android Webview with authendication

I am working in an android application an I want to open a pdf from a link in an android webview. But the link has implemented authendication. I am not able to open that link with pdf.But if I place a link without the pdf, I am able to see the web page in the android webview.So the authendication works fine. The problem is when I append "https://docs.google.com/gview?embedded=true&url=" to the url to open the pdf.

Please look into my code.

public class MainActivity extends Activity {

    @SuppressLint("SetJavaScriptEnabled")
    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        WebView webview = new WebView(MainActivity.this);
        webview.getSettings().setJavaScriptEnabled(true);
        String url=
                 "https://docs.google.com/gview?embedded=true&url=" +"http://spahousingli.evero.com/SPADocuments/Forms/Clients/Admissions/ADM000000011.pdf";


        webview.loadUrl(url);
        webview.setWebViewClient(new WebViewClient() {
            public void onReceivedHttpAuthRequest(WebView view,
                    android.webkit.HttpAuthHandler handler, String host,
                    String realm) {

                handler.proceed("username", "password");
            };
        });
        setContentView(webview);

    }   
}