old_contents: import React, { Component, PropTypes } from 'react';
  
  class Counter extends Component {
    constructor() {
      super();
      this.state = { counter: 0 };
      
      this.increment = this.increment.bind(this);
      this.decrement = this.decrement.bind(this);
    }
  
    increment() {
      const state = { counter: this.state.counter + 1 };
      this.setState(state);
    }
  
    decrement() {
      const state = { counter: this.state.counter - 1 };
      this.setState(state);
    }
  
    render() {
      const { counter } = this.state;
      return (
        <p>
          Clicked: {counter} times
          {' '}
          <button onClick={this.increment}>+</button>
          {' '}
          <button onClick={this.decrement}>-</button>
        </p>
      );
    }
  }
  
  export default Counter;
  
new_contents: import React, { Component, PropTypes } from 'react';
  
  class Counter extends Component {
    constructor() {
      super();
      this.state = { counter: 0 };
      
      this.increment = this.increment.bind(this);
      this.decrement = this.decrement.bind(this);
    }
  
    increment() {
      const state = { counter: this.state.counter + 1 };
      window.devToolsExtension && window.devToolsExtension.send('increment', state);
      this.setState(state);
    }
  
    decrement() {
      const state = { counter: this.state.counter - 1 };
      window.devToolsExtension && window.devToolsExtension.send('decrement', state);
      this.setState(state);
    }
  
    render() {
      const { counter } = this.state;
      return (
        <p>
          Clicked: {counter} times
          {' '}
          <button onClick={this.increment}>+</button>
          {' '}
          <button onClick={this.decrement}>-</button>
        </p>
      );
    }
  }
  
  export default Counter;
  
subject: Send changes in react-counter-messaging