Examine source code of Tel Linker

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "name": "Tel Linker",
  "version": "0.5.4resigned1",
  "manifest_version": 2,
  "description": "Locates telephone numbers on a page and converts them into clickable links.",
  "permissions": [
    "storage",
    "contextMenus",
    "tabs"
  ],
  "background": {
    "persistent": false,
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*",
        "file:///*/*"
      ],
      "js": [
        "content_script.js"
      ],
      "run_at": "document_idle",
      "all_frames": true
    }
  ],
  "browser_action": {
    "default_title": "Tel Linker - Filter",
    "default_popup": "browser_action.html"
  },
  "icons": {
    "16": "icon16.png",
    "128": "icon128.png"
  },
  "options_ui": {
    "page": "options.html",
    "chrome_style": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "ceiihmdnpjglaoolchdmncoffhhbgodj@chrome-store-foxified-1127895862"
    }
  }
}