Examine source code of Pinterest Save Button

{
  "version": "4.2.103",
  "name": "__MSG_extName__",
  "description": "__MSG_extDescription__",
  "default_locale": "en",
  "permissions": [
    "*://*/*",
    "<all_urls>",
    "contextMenus",
    "cookies",
    "storage",
    "tabs",
    "activeTab",
    "webRequest",
    "webRequestBlocking"
  ],
  "background": {
    "scripts": [
      "js/background.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "19": "img/icon_toolbar.png",
      "38": "img/icon_toolbar@2x.png"
    },
    "default_title": "__MSG_saveAction__"
  },
  "content_scripts": [
    {
      "js": [
        "js/content.js"
      ],
      "matches": [
        "*://*/*"
      ],
      "all_frames": true
    }
  ],
  "icons": {
    "16": "img/icon_16.png",
    "48": "img/icon_48.png",
    "128": "img/icon_128.png",
    "140": "img/icon_140.png",
    "256": "img/icon_256.png"
  },
  "options_ui": {
    "page": "html/options.html",
    "chrome_style": true
  },
  "web_accessible_resources": [
    "/html/save.html"
  ],
  "manifest_version": 2,
  "applications": {
    "gecko": {
      "id": "jid1-YcMV6ngYmQRA2w@jetpack",
      "strict_min_version": "57.0"
    }
  }
}