Examine source code of Better MXR

{
  "applications": {
    "gecko": {
      "id": "jid0-ePBKtqqSeez8ThB1NInNoY7B0xc@jetpack"
    }
  },
  "background": {
    "scripts": [
      "redirect-to-dxr.js"
    ]
  },
  "description": "Redirect MXR to DXR",
  "icons": {
    "64": "icon64.png"
  },
  "manifest_version": 2,
  "name": "Better MXR",
  "permissions": [
    "https://mxr.mozilla.org/*",
    "webRequest",
    "webRequestBlocking"
  ],
  "version": "0.4.2resigned1"
}