// content.js
chrome.runtime.onMessage.addListener(
	function(request, sender, sendResponse) {
	  if( request.message === "clicked_browser_action" ) {
		var firstHref = $("a[href^='http']").eq(0).attr("href");
  
		console.log(firstHref);
  
		// This line is new!
		chrome.runtime.sendMessage({"message": "open_new_tab", "url": firstHref});
	  }
	}
  );