Examine source code of KeepBackPlay

{
  "manifest_version": 2,
  "version": "0.2.10",
  "name": "KeepBackPlay - Background Playback Fix",
  "short_name": "KeepBackPlay",
  "description": "__MSG_cj_i18n_07937__",
  "author": "Jeurissen Apps",
  "homepage_url": "https://apps.jeurissen.co/keep-back-play",
  "developer": {
    "name": "Jeurissen Apps",
    "url": "https://apps.jeurissen.co/"
  },
  "default_locale": "en",
  "content_security_policy": "default-src 'none'; child-src 'none'; connect-src 'none'; font-src 'none'; frame-src 'none'; manifest-src 'none'; media-src 'none'; object-src 'none'; worker-src 'none'; img-src 'none'; script-src 'self'; script-src-elem 'self'; script-src-attr 'none'; style-src 'self'; style-src-elem 'self'; style-src-attr 'none'; base-uri 'none'; form-action 'none'; frame-ancestors about:; block-all-mixed-content; upgrade-insecure-requests",
  "browser_specific_settings": {
    "gecko": {
      "id": "keep-back-play@apps.jeurissen.co"
    }
  },
  "externally_connectable": {
    "accepts_tls_channel_id": false
  },
  "permissions": [
    "contextMenus",
    "debugger",
    "scripting",
    "storage",
    "<all_urls>",
    "http://*/**",
    "https://*/**"
  ],
  "icon_variants": [
    {
      "16": "/images/icon-dark-16.svg",
      "color_schemes": [
        "dark"
      ]
    },
    {
      "16": "/images/icon-16.svg"
    },
    {
      "16": "/images/icon-16.png",
      "24": "/images/icon-24.png",
      "32": "/images/icon-32.png",
      "48": "/images/icon-48.png",
      "64": "/images/icon-64.png",
      "96": "/images/icon-96.png",
      "128": "/images/icon-128.png",
      "256": "/images/icon-256.png"
    }
  ],
  "background": {
    "page": "/views/background.html",
    "persistent": false
  },
  "options_ui": {
    "page": "/views/options.html"
  },
  "commands": {
    "_execute_browser_action": {
      "description": "__MSG_cj_i18n_07096__"
    }
  },
  "content_scripts": [
    {
      "run_at": "document_start",
      "all_frames": true,
      "js": [
        "/scripts/cs-isolated.js"
      ],
      "matches": [
        "https://*/**",
        "http://*/**"
      ]
    }
  ],
  "icons": {
    "16": "/images/icon-16.png",
    "24": "/images/icon-24.png",
    "32": "/images/icon-32.png",
    "48": "/images/icon-48.png",
    "64": "/images/icon-64.png",
    "96": "/images/icon-96.png",
    "128": "/images/icon-128.png",
    "256": "/images/icon-256.png"
  },
  "options_page": "/views/options.html",
  "browser_action": {
    "browser_style": false,
    "default_title": "__MSG_cj_i18n_07938__",
    "default_popup": "/views/popup.html",
    "icon_variants": [
      {
        "16": "/images/icon-dark-16.svg",
        "color_schemes": [
          "dark"
        ]
      },
      {
        "16": "/images/icon-16.svg"
      },
      {
        "16": "/images/icon-16.png",
        "24": "/images/icon-24.png",
        "32": "/images/icon-32.png",
        "48": "/images/icon-48.png",
        "64": "/images/icon-64.png"
      }
    ],
    "default_icon": {
      "16": "/images/icon-16.png",
      "24": "/images/icon-24.png",
      "32": "/images/icon-32.png",
      "48": "/images/icon-48.png",
      "64": "/images/icon-64.png"
    },
    "theme_icons": [
      {
        "dark": "/images/icon-16.svg",
        "light": "/images/icon-dark-16.svg",
        "size": 16
      },
      {
        "dark": "/images/icon-16.svg",
        "light": "/images/icon-dark-16.svg",
        "size": 24
      },
      {
        "dark": "/images/icon-16.svg",
        "light": "/images/icon-dark-16.svg",
        "size": 32
      },
      {
        "dark": "/images/icon-16.svg",
        "light": "/images/icon-dark-16.svg",
        "size": 48
      },
      {
        "dark": "/images/icon-16.svg",
        "light": "/images/icon-dark-16.svg",
        "size": 64
      }
    ]
  },
  "applications": {
    "gecko": {
      "id": "keep-back-play@apps.jeurissen.co"
    }
  }
}