title: onDismiss function in snackbar doesn't work in react-native-paper
body: <p>I'm building mobile application with <code>react-native</code> and <code>react-native-paper</code>.
  And I'm using <code>SnackBar</code> component in <code>react-native-paper</code>, and if I use <code>SnackBar</code> component directly, <code>onDismiss</code> function in <code>SnackBar</code> component works well. (It means the snackbar will disappear correctly)</p>
  
  <p>But if I use my original component(like <code>SnackBarComponent</code> component) which uses <code>SnackBar</code> component provided <code>react-native-paper</code>, somehow, the snackbar will not disappear correctly.</p>
  
  <p>This is my custom SnackBar Component and the code which calls my original SnackBar Component.</p>
  
  <ul>
  <li>My original SnackBar Component</li>
  </ul>
  
  <pre><code>import React, { Component } from 'react';
  import { Text } from 'react-native';
  import { Provider, Snackbar } from 'react-native-paper';
  
  export default class SnackBarComponent extends Component {
    constructor(props) {
      super(props);
      this.state = {
        snackbarVisible: false
      }
    }
  
    render() {
      return(
        &lt;Provider&gt;
          &lt;Snackbar
            visible={this.props.snackbarVisible}
            onDismiss={() =&gt; this.setState({ snackbarVisible: false })}
          &gt;
            &lt;Text&gt;{this.props.snackbarText}&lt;/Text&gt;
          &lt;/Snackbar&gt;
        &lt;/Provider&gt;
      )
    }
  }
  </code></pre>
  
  <ul>
  <li>The code which calls SnackBarComponent(This is not whole code)</li>
  </ul>
  
  <pre><code>import SnackBarComponent from './components/SnackBarComponent';
  
  :
  
  handleShowSnackbar() {
    this.setState({
      snackbarVisible: true,
      snackbarText: 'show snackbar'
    })
  }
  
  :
  
  &lt;SnackBarComponent snackbarVisible={this.state.snackbarVisible} snackbarText={this.state.snackbarText}/&gt;
  
  :
  </code></pre>