Add progressbar in my webview

Hello, I want to add a progress bar in my webview .

I saw a tutorial and it did not work properly, because the progress bar is loading forever.

I will post the code as it was, I wanted the progress bar to appear only when loading the page, code I have:

public class MainActivity extends Activity {

    private ProgressBar pb;
    private WebView wv;
    private String URL = "http://www.google.com.br";

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

        ActionBar actionBar = getActionBar();
        actionBar.hide();
        wv = (WebView) findViewById(R.id.webView1);
        pb = (ProgressBar)findViewById(R.id.progressBar1);

        carregarSite();

    }


    public void carregarSite() {

        try {
            // Verifica conexão
            if (verificaConexao()) {
                // Ajusta algumas configurações
                WebSettings ws = wv.getSettings();
                ws.setJavaScriptEnabled(true);
                ws.setBuiltInZoomControls(true);
                wv.setWebViewClient(new WebViewClient());
                wv.setWebChromeClient(new WebChromeClient());
                wv.loadUrl(URL);
            }

            else
                msgConexao();
        } catch (Exception e) {
            Toast.makeText(MainActivity.this, "Erro ao carregar o site", 1000)
                    .show();
        }
    }

    @Override
    public void onBackPressed() {

        msgExit();

    }

    private class MyWebViewClient extends WebViewClient {   
         @Override
            public boolean shouldOverrideUrlLoading(WebView view, String url) {
                view.loadUrl(url);
                return true;
            }

         @Override
        public void onPageFinished(WebView view, String url) {
             pb.setVisibility(View.GONE);
            super.onPageFinished(view, url);
        }

         @Override
        public void onPageStarted(WebView view, String url, Bitmap favicon) {

            super.onPageStarted(view, url, favicon);
        }

    }
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        // TODO Auto-generated method stub
        if((keyCode == KeyEvent.KEYCODE_BACK) && wv.canGoBack())
        {
            wv.goBack();
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }

}

Layout:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"

    tools:ignore="MergeRootFrame" >

    <WebView
        android:id="@+id/webView1"
        android:layout_width="match_parent"
        android:layout_height="357dp"
        android:layout_weight="1.78" />


    <ProgressBar
        android:id="@+id/progressBar1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
         android:layout_gravity="center"
         />

</LinearLayout>