{
  "content_scripts": [
    {
      "matches": ["http://exifdata.com/"], // sample site
      "js": ["index.js"]
    }
  ],
  "manifest_version": 2,
  "name": "Test",
  "version": "0.0.0"
}

function fileToDataView(file) {
  var reader = new FileReader();
  reader.onload = function (e) {
    console.log(new DataView(e.target.result));
  };
  reader.onerror = function (error) {
    console.log(error); // no error occurs
  };
  reader.readAsArrayBuffer(file);
}

var nodes = document.querySelectorAll('input[type=file]')

nodes.forEach(function (node) {
  node.onchange = function (event) {
    fileToDataView(event.target.files[0]);
  }
})