sendbird_utilities_bar.cmp

<aura:component implements="flexipage:availableForAllPageTypes" access="global" >
  <lightning:utilityBarAPI aura:id="utilitybar" />
  <aura:attribute name="recordId" type="String" />
  <aura:attribute name="data" type="String" />
  <lightning:navigation aura:id="navService" />
  <aura:handler name="init" value="{!this}" action="{!c.doInit }  " />
  <lightning:container
    aura:id="SendBird_Bar"
    src="{!$Resource.sendbird_bar + '/index.html'}"
    onmessage="{!c.handleMessage}"
  />

  <!-- optional loading spinner -->
  <aura:attribute name="toggleSpinner" type="boolean" default="true" />
  <aura:if isTrue="{!v.toggleSpinner}">
    <div class="exampleHolder">
      <lightning:spinner alternativeText="Loading" size="large" />
    </div>
  </aura:if>
</aura:component>

sendbird_utilities_barController.js

({
  handleError: function(component, event, helper) {
    var error = event.getParams();
    console.log("Error from Utilities Bar:", error);
  },
  handleMessage: function(component, message, helper) {
    var payload = message.getParams().payload;
    var event = payload.event;
    console.log("MESSAGE ARRIVED IN UTILITIES BAR", message);
    if (payload === "READY") helper.initUIKit(component, message, helper);
    if (event === "NEWMESSAGE")
      helper.newSendbirdUserMessageArrived(component, message, helper);
  }
});

sendbird_utilities_barHelper.js

({
  initUIKit: function(component, message, helper) {
    var userId = $A.get("$SObjectType.CurrentUser.Id");
    var message = { userId: userId };
    try {
      component.set("v.toggleSpinner", false);
      component.find("SendBird_Bar").message(message);
      console.warn("SALEFORCE --> Lightning Component --> Sent:", message);
    } catch (err) {
      console.error("Error from Utilities Bar:", err);
    }
  },
  newSendbirdUserMessageArrived: function(component, message, helper) {
    var payload = message.getParams().payload;
    var unreadCount = payload.unreadCount;
    console.warn(
      "Lightning Container --> SALESFORCE --> unread count arrived:",
      unreadCount
    );
    var utilityAPI = component.find("utilitybar");
    console.log(utilityAPI)  
    utilityAPI.setUtilityLabel({
      label: "Unread Messages"
    });
    utilityAPI.setUtilityIcon({
      icon: "chat",
      options: { iconVariant: "success", fill: "green" }
    });
  }
});