Examine source code of StumbleUponAwesome

{
  "name": "StumbleUponAwesome",
  "manifest_version": 2,
  "version": "1.2.2",
  "description": "An awesome internet discovery button. Like StumbleUpon, but for developers, tech and science lovers.",
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "web_accessible_resources": [
    "images/icon_16.png",
    "images/icon_32.png",
    "images/icon_128.png",
    "images/rabbithole.gif",
    "images/rabbithole.png",
    "images/rabbithole_small.png",
    "images/spiral.png",
    "images/close.svg"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "css": [
        "styles.css"
      ],
      "run_at": "document_idle",
      "js": [
        "content.js"
      ]
    }
  ],
  "permissions": [
    "storage",
    "contextMenus"
  ],
  "browser_action": {
    "default_icon": {
      "16": "images/icon_16.png",
      "32": "images/icon_32.png",
      "48": "images/icon_48.png",
      "128": "images/icon_128.png"
    }
  },
  "icons": {
    "16": "images/icon_16.png",
    "32": "images/icon_32.png",
    "48": "images/icon_48.png",
    "128": "images/icon_128.png"
  },
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "windows": "Alt+Shift+S",
        "mac": "Alt+Shift+S",
        "chromeos": "Alt+Shift+S",
        "linux": "Alt+Shift+S"
      }
    }
  }
}