Examine source code of Sisu grade distribution

{
  "manifest_version": 2,
  "name": "Sisu grade distribution for firefox",
  "version": "1.0",
  "description": "Creates a chart of grade distibution on sisu page. Inspiration is from chrome extension which was created ealier by Aapo Laakkio.",
  "permissions": [
    "https://sisu.aalto.fi/*",
    "webRequest",
    "webRequestBlocking",
    "webRequestFilterResponse"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "https://sisu.aalto.fi/*"
      ],
      "js": [
        "libs/chart.min.js",
        "content.js"
      ],
      "run_at": "document_end"
    }
  ],
  "browser_action": {
    "default_title": "Sisu grade distribution"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{620194a8-0333-47b0-8c55-0c015798a610}"
    }
  }
}