Examine source code of GitHub Writer

{
  "name": "GitHub Writer",
  "description": "A WYSIWYG rich-text editor for GitHub issues, comments and pull requests. Powered by CKEditor.",
  "version": "1.10.4",
  "author": "CKSource (https://cksource.com)",
  "permissions": [
    "https://*.s3.amazonaws.com/"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://github.com/issues",
        "https://github.com/*/issues",
        "https://github.com/*/issues/*",
        "https://github.com/*/pull/*",
        "https://github.com/*/commit/*",
        "https://github.com/*/compare/*",
        "https://github.com/*/releases/*",
        "https://github.com/*/milestones",
        "https://github.com/*/milestones/*",
        "https://github.com/*/wiki/_new*",
        "https://github.com/*/wiki/*/_edit",
        "https://github.com/settings/*"
      ],
      "js": [
        "github-writer.js"
      ],
      "css": [
        "github-writer.css"
      ],
      "run_at": "document_end"
    }
  ],
  "icons": {
    "16": "icons/github-writer-16.png",
    "32": "icons/github-writer-32.png",
    "48": "icons/github-writer-48.png",
    "96": "icons/github-writer-96.png",
    "128": "icons/github-writer-128.png"
  },
  "browser_action": {
    "default_popup": "popup/popup.html",
    "default_title": "GitHub Writer"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "github-writer@cksource.com"
    }
  },
  "manifest_version": 2
}