Android WebView - Splash/Loading screen (incomplete)

MainActivity.java

package com.diamondium.samplewebview;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.graphics.Bitmap;
import android.view.View;
import android.widget.ProgressBar;

public class MainActivity extends AppCompatActivity {

    private WebView webview ;
    private ProgressBar spinner;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        webview =(WebView)findViewById(R.id.webView);
        spinner = (ProgressBar)findViewById(R.id.progressBar1);
        webview.setWebViewClient(new CustomWebViewClient());

        webview.getSettings().setJavaScriptEnabled(true);
        webview.getSettings().setDomStorageEnabled(true);
        webview.setOverScrollMode(WebView.OVER_SCROLL_NEVER);
        webview.loadUrl("https://www.google.com");

    }

    // This allows for a splash screen
    // (and hide elements once the page loads)
    private class CustomWebViewClient extends WebViewClient {

        @Override
        public void onPageStarted(WebView webview, String url, Bitmap favicon) {
            webview.setVisibility(webview.INVISIBLE);
        }

        @Override
        public void onPageFinished(WebView view, String url) {

            spinner.setVisibility(View.GONE);

            view.setVisibility(webview.VISIBLE);
            super.onPageFinished(view, url);

        }
    }

}