Examine source code of Copyf

{
  "description": "Copy formatted somthing to clipboard",
  "manifest_version": 2,
  "name": "copyf",
  "version": "1.7.8",
  "icons": {
    "48": "icon/ic_content_copy_black_48dp_1x.png"
  },
  "background": {
    "scripts": [
      "js/background.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "18": "icon/ic_content_copy_black_18dp_1x.png",
      "24": "icon/ic_content_copy_black_24dp_1x.png",
      "36": "icon/ic_content_copy_black_36dp_1x.png",
      "48": "icon/ic_content_copy_black_48dp_1x.png",
      "72": "icon/ic_content_copy_black_36dp_2x.png",
      "96": "icon/ic_content_copy_black_48dp_2x.png"
    },
    "theme_icons": [
      {
        "light": "icon/ic_content_copy_white_18dp_1x.png",
        "dark": "icon/ic_content_copy_black_18dp_1x.png",
        "size": 18
      },
      {
        "light": "icon/ic_content_copy_white_24dp_1x.png",
        "dark": "icon/ic_content_copy_black_24dp_1x.png",
        "size": 24
      },
      {
        "light": "icon/ic_content_copy_white_36dp_1x.png",
        "dark": "icon/ic_content_copy_black_36dp_1x.png",
        "size": 36
      },
      {
        "light": "icon/ic_content_copy_white_48dp_1x.png",
        "dark": "icon/ic_content_copy_black_48dp_1x.png",
        "size": 48
      },
      {
        "light": "icon/ic_content_copy_white_36dp_2x.png",
        "dark": "icon/ic_content_copy_black_36dp_2x.png",
        "size": 72
      },
      {
        "light": "icon/ic_content_copy_white_48dp_2x.png",
        "dark": "icon/ic_content_copy_black_48dp_2x.png",
        "size": 96
      }
    ],
    "default_title": "copyf",
    "default_popup": "html/popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "js/content.js"
      ],
      "run_at": "document_start",
      "all_frames": false
    }
  ],
  "options_ui": {
    "page": "html/option.html"
  },
  "permissions": [
    "<all_urls>",
    "clipboardWrite",
    "tabs",
    "storage",
    "notifications"
  ],
  "applications": {
    "gecko": {
      "id": "copyf@snca.net",
      "strict_min_version": "57.0"
    }
  },
  "content_security_policy": "script-src 'self' 'unsafe-eval'; object-src 'self';"
}