Reload an img tag's image data through an extension's background page.

content-script.js

function onExtensionImgError(e) {
  var img = e.target;
  var tagName = img.tagName.toLowerCase();
  var wasReattempted = img.dataset.myExtensionReattempted;
  var reattempt = (!wasReattempted && tagName === 'img' && isHttpUrl(img.src) && extensionContains(img));
  if (reattempt) {
    img.dataset.myExtensionReattempted = true;
    api.port.emit('load_image', img.src, function onRespond(data) {
      var err = data.error;
      if (!err) {
        img.src = data.uri;
      } else {
        console.log('[onExtensionImgError] Could not fix image: %s', err);
      }
    });
  }
}