{
  "background": {
    "scripts": [
      "js/background.js"
    ]
  },
  "browser_action": {},
  "description": "Display how many tabs are open.",
  "manifest_version": 2,
  "name": "Tab Counter",
  "permissions": [
    "tabs"
  ],
  "version": "0.0.1"
}

{
  "applications": {
    "gecko": {
      "id": "tab-counter@example.com"
    }
  },
  "background": {
    "scripts": [
      "js/background.js"
    ]
  },
  "browser_action": {},
  "description": "Display how many tabs are open.",
  "manifest_version": 2,
  "name": "Tab Counter",
  "permissions": [
    "tabs"
  ],
  "version": "0.0.1"
}

Add setting for extension to load in Firefox
Add setting for extension to load in Firefox
