Examine source code of Effin' Birds

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  "description": "__MSG_extensionDescription__",
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  "homepage_url": "https://twitter.com/effinbirds",
  "default_locale": "en",
  "applications": {
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      "id": "effin-birds@jorgev"
    }
  },
  "icons": {
    "48": "icons/effin-48.png",
    "96": "icons/effin-96.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "https://*.tumblr.com/*",
    "storage"
  ],
  "browser_action": {
    "default_icon": {
      "16": "button/effin-16.png",
      "32": "button/effin-32.png",
      "64": "button/effin-64.png"
    },
    "default_title": "Effin' Birds",
    "default_popup": "popup/birds.html"
  }
}