Examine source code of Page Shadow

{
  "name": "Page Shadow",
  "version": "2.11.5",
  "default_locale": "en",
  "manifest_version": 2,
  "icons": {
    "32": "img/icon_32.png",
    "40": "img/icon_40.png",
    "48": "img/icon_48.png",
    "64": "img/icon.png",
    "96": "img/icon_96.png",
    "128": "img/icon_128.png",
    "256": "img/icon_256.png",
    "512": "img/icon_512.png"
  },
  "description": "__MSG_extensionDescription__",
  "author": "Eliastik",
  "developer": {
    "name": "Eliastik",
    "url": "http://www.eliastiksofts.com/page-shadow/"
  },
  "homepage_url": "http://www.eliastiksofts.com/page-shadow/",
  "browser_action": {
    "default_title": "Page Shadow",
    "default_icon": {
      "32": "img/icon_32.png",
      "40": "img/icon_40.png",
      "48": "img/icon_48.png",
      "64": "img/icon.png",
      "96": "img/icon_96.png",
      "128": "img/icon_128.png",
      "256": "img/icon_256.png",
      "512": "img/icon_512.png"
    }
  },
  "options_ui": {
    "open_in_tab": true,
    "page": "options.html"
  },
  "applications": {
    "gecko": {
      "id": "page-shadow@eliastiksofts.com",
      "strict_min_version": "58.0"
    }
  },
  "permissions": [
    "storage",
    "contextMenus",
    "tabs",
    "<all_urls>",
    "unlimitedStorage"
  ],
  "content_scripts": [
    {
      "js": [
        "js/content.js"
      ],
      "css": [
        "css/content.css",
        "css/content_invert.css",
        "css/content_attenuate.css"
      ],
      "matches": [
        "http://*/*",
        "https://*/*",
        "ftp://*/*",
        "file:///*/*"
      ],
      "run_at": "document_start",
      "match_about_blank": true,
      "all_frames": true
    }
  ],
  "background": {
    "scripts": [
      "js/background.js"
    ]
  },
  "commands": {
    "enableDisable": {
      "suggested_key": {
        "default": "Alt+Shift+S"
      },
      "description": "__MSG_enableDisableShortcut__"
    },
    "enablePresetOne": {
      "description": "__MSG_enablePresetOne__"
    },
    "enablePresetTwo": {
      "description": "__MSG_enablePresetTwo__"
    },
    "enablePresetThree": {
      "description": "__MSG_enablePresetThree__"
    },
    "enablePresetFour": {
      "description": "__MSG_enablePresetFour__"
    },
    "enablePresetFive": {
      "description": "__MSG_enablePresetFive__"
    },
    "enablePresetSix": {
      "description": "__MSG_enablePresetSix__"
    },
    "enablePresetSeven": {
      "description": "__MSG_enablePresetSeven__"
    },
    "enablePresetEight": {
      "description": "__MSG_enablePresetEight__"
    },
    "enablePresetNine": {
      "description": "__MSG_enablePresetNine__"
    },
    "enablePresetTen": {
      "description": "__MSG_enablePresetTen__"
    },
    "enablePresetEleven": {
      "description": "__MSG_enablePresetEleven__"
    },
    "enablePresetTwelve": {
      "description": "__MSG_enablePresetTwelve__"
    },
    "enablePresetThirteen": {
      "description": "__MSG_enablePresetThirteen__"
    },
    "enablePresetFourteen": {
      "description": "__MSG_enablePresetFourteen__"
    },
    "enablePresetFifteen": {
      "description": "__MSG_enablePresetFifteen__"
    }
  }
}