hrtools/content/inject.js

if( window.location.href === "http://localhost:12203/start") {

    var ws = new WebSocket("ws://localhost:12203/task");
    ws.onopen = function(evt) {  
        console.log("Connection open ...", evt);  
        ws.send("Hello WebSockets!");  
    };  
    
    ws.onmessage = function(evt) {  
        console.log("Received Message: ", JSON.parse(evt.data));
        chrome.runtime.sendMessage(JSON.parse(evt.data))
    };  
    
    ws.onclose = function(evt) {  
        console.log("Connection closed.");  
    };
    
    ws.onerror = function(evt) {
      console.log(evt);
    }
    
}