Remove createReactClass from ProgressBarAndroidExample (#21874)

Summary:
Related to #21581

This PR was already opened here https://github.com/facebook/react-native/pull/21600 but seems to be inactive.

Remove createReactClass from ProgressBarAndroidExample.

- `yarn run flow` && `yarn run flow-check-android` succeed.
- RNTester app ProgressBarAndroidExample on Android.

[GENERAL] [ENHANCEMENT] [ProgressBarAndroidExample.android.js] - rm createReactClass
Pull Request resolved: https://github.com/facebook/react-native/pull/21874

Reviewed By: TheSavior

Differential Revision: D12827689

Pulled By: RSNara

fbshipit-source-id: 46c70ea67dddf5d928fe936a28ef4a0a929d127f

RNTester/js/ProgressBarAndroidExample.android.js

@@ -12,37 +12,49 @@
 
 const ProgressBar = require('ProgressBarAndroid');
 const React = require('React');
-const createReactClass = require('create-react-class');
 const RNTesterBlock = require('RNTesterBlock');
 const RNTesterPage = require('RNTesterPage');
 
-const MovingBar = createReactClass({
-  displayName: 'MovingBar',
-  _intervalID: (null: ?IntervalID),
+import type {ProgressBarAndroidProps} from 'ProgressBarAndroid';
 
-  getInitialState: function() {
-    return {
-      progress: 0,
-    };
-  },
+type MovingBarProps = $ReadOnly<{|
+  ...$Diff<
+    ProgressBarAndroidProps,
+    {
+      progress: ?number,
+    },
+  >,
+  indeterminate: false,
+|}>;
 
-  componentDidMount: function() {
+type MovingBarState = {
+  progress: number,
+};
+
+class MovingBar extends React.Component<MovingBarProps, MovingBarState> {
+  _intervalID: ?IntervalID = null;
+
+  state = {
+    progress: 0,
+  };
+
+  componentDidMount() {
     this._intervalID = setInterval(() => {
       const progress = (this.state.progress + 0.02) % 1;
-      this.setState({progress: progress});
+      this.setState({progress});
     }, 50);
-  },
+  }
 
-  componentWillUnmount: function() {
+  componentWillUnmount() {
     if (this._intervalID != null) {
       clearInterval(this._intervalID);
     }
-  },
+  }
 
-  render: function() {
+  render() {
     return <ProgressBar progress={this.state.progress} {...this.props} />;
-  },
-});
+  }
+}
 
 class ProgressBarAndroidExample extends React.Component<{}> {
   static title = '<ProgressBarAndroid>';