Examine source code of Font Contrast

{
  "name": "Font Contrast",
  "description": "Improves webpage readability.",
  "version": "1.6.1",
  "author": "Francesco Fusco",
  "permissions": [
    "http://*/*",
    "https://*/*",
    "storage",
    "tabs",
    "file:///*"
  ],
  "background": {
    "scripts": [
      "src/background.js"
    ]
  },
  "options_ui": {
    "page": "options.html",
    "browser_style": false,
    "open_in_tab": false
  },
  "browser_action": {
    "browser_style": true,
    "default_icon": "assets/icons/off.png",
    "default_title": "Apply contrast fix!"
  },
  "page_action": {
    "default_icon": {
      "16": "assets/icons/halo.png",
      "24": "assets/icons/halo.png",
      "32": "assets/icons/halo.png"
    },
    "default_title": "Manage Font Contrast for this website",
    "default_popup": "pageAction_popup.html",
    "browser_style": false
  },
  "icons": {
    "16": "assets/icons/on.png",
    "48": "assets/icons/on.png",
    "128": "assets/icons/on.png"
  },
  "manifest_version": 2,
  "commands": {
    "toggle": {
      "suggested_key": {
        "default": "Shift+F1"
      },
      "description": "Toggle contrast fix"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{80f6f2e4-eda1-417f-bf54-9645e1e20f5d}"
    }
  }
}