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}"
    }
  }
}