Examine source code of UpComment

{
  "manifest_version" : 2 ,
  "name" : "UpComment",
  "description" : "Web Extension for comment to any sites",
  "version" : "0.0.1",
  "icons" : {
    "16" : "icon/16.png",
    "32" : "icon/32.png",
    "48" : "icon/48.png",
    "96" : "icon/96.png",
    "128" : "icon/128.png"
  },
  "permissions" : [
    "tabs" ,
    "scripting" ,
    "sidePanel" ,
    "cookies" ,
    "storage" ,
    "webNavigation" ,
    "*://*/*" 
  ],
  "background" : {
    "scripts" : [
      "background.js" 
    ]
  },
  "browser_action" : {},
  "sidebar_action": {
    "default_panel": "sidepanel.html",
    "browser_style": true,
    "default_icon" : {
      "16" : "/icon/16.png",
      "32" : "/icon/32.png",
      "48" : "/icon/48.png",
      "96" : "/icon/96.png",
      "128" : "/icon/128.png"
    },
    "default_title" : "UpComment",
    "open_at_install": true
  },
  "content_scripts" : [
    {
      "matches" : [
        "<all_urls>" 
      ],
      "run_at" : "document_start" ,
      "js" : [
        "content-scripts/content.js" 
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{1f77d968-553e-48e2-b966-2d5a9e413876}"
    }
  }
}