Examine source code of GrayscaleToggle

{
  "manifest_version": 2,
  "name": "__MSG_extensionName__",
  "version": "1.0.0",
  "description": "__MSG_extensionDescription__",
  "permissions": [
    "storage",
    "activeTab",
    "tabs",
    "contextMenus",
    "https://*/*",
    "http://*/*"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "48": "icons/icon-48.png",
      "96": "icons/icon-96.png"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "commands": {
    "toggle_reader_mode": {
      "suggested_key": {
        "default": "Ctrl+Shift+R",
        "mac": "Command+Shift+R"
      },
      "description": "Toggle Reader Mode"
    }
  },
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "content.css"
      ]
    }
  ],
  "web_accessible_resources": [
    "icons/*",
    "fonts/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{335977e6-1175-4adf-a330-f4a580bd6888}"
    }
  }
}