activity.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:ads="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <com.google.android.gms.ads.NativeExpressAdView
        android:id="@+id/adView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        ads:adSize="FULL_WIDTHx80"
        ads:adUnitId="@string/ad_unit_id"
        android:visibility="gone"
        android:background="@color/btnGray"

        >
    </com.google.android.gms.ads.NativeExpressAdView>
    <ProgressBar
        android:id="@+id/progressbar"
        style="?android:attr/progressBarStyleHorizontal"
        android:layout_width="match_parent"
        android:layout_height="4dp"
        android:layout_marginTop="0.01dp"
        android:max="100"
        android:progress="50"
        android:progressDrawable="@drawable/webview_progressbar"
        android:secondaryProgress="0" />
    
    <WebView
        android:id="@+id/webView"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>