Examine source code of Opal Developer Tools

{
  "manifest_version": 2,
  "name": "OpalDeveloperTools",
  "description": "Tools for working with Opal Ruby in the browser.",
  "version": "0.0.3",
  "author": "Jan Biedermann",
  "homepage_url": "https://github.com/isomorfeus/opal-devtools",
  "applications": {
    "gecko": {
      "id": "@opal-devtools"
    }
  },
  "icons": {
    "48": "icons/opal_devtools_48_t.png",
    "128": "icons/opal_devtools_128_t.png"
  },
  "permissions": [
    "<all_urls>",
    "activeTab"
  ],
  "devtools_page": "devtools/devtools-page.html",
  "background": {
    "scripts": [
      "background_scripts/background.js"
    ]
  }
}