Examine source code of Reading Speed Test

{
  "manifest_version": 2,
  "name": "Reading Speed Test",
  "description": "This extension lets you measure your reading speed on any web text.",
  "version": "1.1",
  "default_locale": "en",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "19": "icon_wip10_19.png",
      "38": "icon_wip10_38.png"
    },
    "default_popup": "popup.html"
  },
  "icons": {
    "16": "icon_wip10_16.png",
    "32": "icon_wip10_32.png",
    "64": "icon_wip10_64.png",
    "128": "icon_wip10_128.png"
  },
  "permissions": [
    "activeTab",
    "contextMenus"
  ],
  "web_accessible_resources": [
    "close_16.png"
  ]
}