Examine source code of Hide This Element

{
  "manifest_version": 2,
  "name": "Element Hider",
  "version": "1.0",
  "description": "Hide elements from the page",
  "permissions": [
    "activeTab",
    "contextMenus"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "element_hider@element_hider"
    }
  }
}