Examine source code of Google+ Share

{
  "manifest_version": 2,
  "name": "Google+ Share",
  "version": "2.0.2resigned1",
  "description": "With Google+ Share you can share your actual webpage with a simple click",
  "homepage_url": "http://adrianistan.eu/norax/",
  "icons": {
    "32": "data/icon32.png",
    "64": "data/icon64.png"
  },
  "applications": {
    "gecko": {
      "id": "google@divel",
      "strict_min_version": "50.0"
    }
  },
  "permissions": [
    "notifications",
    "contextMenus",
    "activeTab",
    "tabs"
  ],
  "browser_action": {
    "default_title": "Share on Google+",
    "default_icon": "data/icon64.png"
  },
  "background": {
    "scripts": [
      "background/main.js"
    ]
  }
}