Examine source code of Insertables

{
  "description": "Click the toolbar button to choose/add/remove frequent text for webpages. Insertables are common text snippets you frequently enter into webpages. Just simply drag the insertable into any input box on a webpage.",
  "manifest_version": 2,
  "name": "Insertable",
  "author": "David Freer",
  "version": "1.1",
  "homepage_url": "https://github.com/soulshined/insertable",
  "icons": {
    "48": "icons/page48.png"
  },
  "permissions": [
    "activeTab",
    "storage",
    "tabs"
  ],
  "browser_action": {
    "theme_icons": [
      {
        "light": "icons/page16-light.png",
        "dark": "icons/page16.png",
        "size": 16
      },
      {
        "light": "icons/page32-light.png",
        "dark": "icons/page32.png",
        "size": 32
      }
    ],
    "default_title": "Insertable",
    "default_popup": "popup/index.html"
  },
  "options_ui": {
    "page": "options/options.html",
    "browser_style": true
  }
}