tachiyomi/app/src/main/res/layout/webview_activity.xml

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

    <com.google.android.material.appbar.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <com.google.android.material.appbar.MaterialToolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            android:theme="?attr/actionBarTheme"
            app:navigationIcon="@drawable/ic_close_24dp" />

    </com.google.android.material.appbar.AppBarLayout>

    <eu.kanade.tachiyomi.widget.ThemedSwipeRefreshLayout
        android:id="@id/swipe_refresh"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <WebView
            android:id="@+id/webview"
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <com.google.android.material.progressindicator.LinearProgressIndicator
                android:id="@+id/progress_bar"
                android:layout_width="match_parent"
                android:layout_height="wrap_content" />

        </WebView>

    </eu.kanade.tachiyomi.widget.ThemedSwipeRefreshLayout>

</LinearLayout>