chrome.extension.onMessage.addListener Cannot read property 'onMessage' of undefined

In the background.html:

chrome.tabs.query({active:true, currentWindow:true},function(tabs){
  chrome.tabs.sendMessage(tabs[0].id,"target.js");
});

In the content.js:

chrome.extension.onMessage.addListener(function(msg,sender,sendResponse){
  if (msg == "target.js"){
    extensionID = sender.id;
  }
});

However, it doesn't work;

Uncaught TypeError: Cannot read property 'onMessage' of undefined 

How to make it right?