@Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            // Respond to the action bar's Up/Home button
            case android.R.id.home:
                finish();
                return true;
        }
        return super.onOptionsItemSelected(item);
    }
This Activity is used as a fallback when there is no browser installed that supports
Chrome Custom Tabs
demos/src/main/java/org/chromium/customtabsdemos/WebviewActivity.java