function changeBackgroundColor(color) {
  var script = 'document.body.style.backgroundColor="' + color + '";';
  // See https://developer.chrome.com/extensions/tabs#method-executeScript.
  // chrome.tabs.executeScript allows us to programmatically inject JavaScript
  // into a page. Since we omit the optional first argument "tabId", the script
  // is inserted into the active tab of the current window, which serves as the
  // default.
  chrome.tabs.executeScript({
    code: script
  });
}
Change the background color of the current page.

@param {string} color The new background color.