Examine source code of Github Dates Filter

{
  "manifest_version" : 2 ,
  "name" : "Github Dates Filter",
  "version" : "1.0.0",
  "description" : "Add a date filter to Github issues and PRs pages.",
  "icons" : {
    "48" : "icons/48.png"
  },
  "content_scripts" : [
    {
      "matches" : [
        "*://*.github.com/*" 
      ],
      "js" : [
        "extension.js" 
      ]
    }
  ]
}