Examine source code of ResizeIT

{
  "browser_action": {
    "browser_style": false,
    "default_icon": {
      "16": "icons/icon_16.png",
      "19": "icons/icon_19.png",
      "38": "icons/icon_38.png",
      "48": "icons/icon_48.png",
      "128": "icons/icon_128.png"
    },
    "default_popup": "html/ResizeIT.html",
    "default_title": "ResizeIT"
  },
  "commands": {
    "Alt1": {
      "description": "Resize Window 1",
      "suggested_key": {
        "chromeos": "Alt+1",
        "default": "Alt+1",
        "linux": "Alt+1",
        "mac": "Alt+1",
        "windows": "Alt+1"
      }
    },
    "Alt2": {
      "description": "Resize Window 2",
      "suggested_key": {
        "chromeos": "Alt+2",
        "default": "Alt+2",
        "linux": "Alt+2",
        "mac": "Alt+2",
        "windows": "Alt+2"
      }
    },
    "Alt3": {
      "description": "Resize Window 3",
      "suggested_key": {
        "chromeos": "Alt+3",
        "default": "Alt+3",
        "linux": "Alt+3",
        "mac": "Alt+3",
        "windows": "Alt+3"
      }
    },
    "Alt4": {
      "description": "Resize Window 4",
      "suggested_key": {
        "chromeos": "Alt+4",
        "default": "Alt+4",
        "linux": "Alt+4",
        "mac": "Alt+4",
        "windows": "Alt+4"
      }
    }
  },
  "description": "Resize Firefox with the 'ALT' keys.",
  "icons": {
    "16": "icons/icon_16.png",
    "48": "icons/icon_48.png",
    "128": "icons/icon_128.png"
  },
  "manifest_version": 2,
  "name": "ResizeIT",
  "author": "Glenn Hallin",
  "permissions": [
    "storage",
    "management"
  ],
  "version": "5.2.1",
  "background": {
    "scripts": [
      "js/ResizeITbg.js"
    ]
  },
  "applications": {
    "gecko": {
      "id": "resizeit@sonej",
      "strict_min_version": "57.0"
    }
  }
}