Examine source code of GitHub Sidebar Button

{
  "manifest_version": 2,
  "name": "GitHub Sidebar Button",
  "version": "2.5",
  "description": "Sidebar with a button that opens GitHub.",
  "permissions": [
    "tabs"
  ],
  "icons": {
    "48": "github-48.png"
  },
  "sidebar_action": {
    "default_title": "GitHub Sidebar",
    "default_panel": "main.html",
    "default_icon": "github-48.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{6ba5f2d4-81bb-455c-8574-37fb213b0365}"
    }
  }
}