Examine source code of tst-tabcount

{
  "manifest_version": 2,
  "name": "tst-tabcount",
  "description": "Generate accurate tabcount for TreeStyleTab CSS",
  "version": "0.0.2",
  "icons": {
    "64": "icons/icon.png"
  },
  "background": {
    "scripts": [
      "background_script.js"
    ]
  },
  "page_action": {
    "default_icon": {
      "64": "icons/icon.png"
    },
    "default_popup": "pageAction/index.html",
    "default_title": "tst-tabcount"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{1b84e1eb-590f-483d-8fd6-16bd467c1a23}"
    }
  }
}