Examine source code of Screengrab! ZS

{
  "manifest_version": 2,
  "name": "__MSG_extension_name__ ZS",
  "short_name": "__MSG_extension_name__ ZS",
  "description": "__MSG_extension_description__ ZS",
  "author": "Oleksandr Popov",
  "version": "2.20",
  "minimum_chrome_version": "45",
  "default_locale": "en",
  "browser_action": {
    "default_icon": {
      "16": "skin/screengrab_24_icon.png"
    },
    "default_popup": "content/popup.html"
  },
  "background": {
    "page": "content/background.html"
  },
  "applications": {
    "gecko": {
      "id": "{a7dc81f6-8507-45ff-a3be-f9a3530597a3}",
      "strict_min_version": "70.0"
    }
  },
  "options_ui": {
    "page": "content/options.html",
    "chrome_style": false,
    "open_in_tab": true
  },
  "permissions": [
    "activeTab",
    "contextMenus",
    "storage",
    "tabs",
    "notifications",
    "unlimitedStorage",
    "clipboardWrite",
    "clipboardRead",
    "webRequest",
    "webRequestBlocking",
    "<all_urls>",
    "downloads",
    "pageCapture"
  ],
  "content_scripts": [
    {
      "js": [
        "/content/hotkeys.js"
      ],
      "matches": [
        "<all_urls>"
      ],
      "run_at": "document_end"
    }
  ],
  "web_accessible_resources": [
    "/skin/*"
  ],
  "icons": {
    "16": "skin/screengrab_16_icon.png",
    "32": "skin/screengrab_32_icon.png",
    "64": "skin/screengrab_64_icon.png",
    "128": "skin/screengrab_128_icon.png"
  }
}