Examine source code of Email Magic

{
  "manifest_version": 2,
  "name": "Email Magic",
  "version": "1.1.2",
  "permissions": [
    "identity",
    "identity.email",
    "storage",
    "activeTab",
    "tabs"
  ],
  "host_permissions": [
    "https://mail.google.com/",
    "https://www.googleapis.com/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "https://mail.google.com/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_action": {
    "default_popup": "options.html",
    "default_icon": {
      "16": "icons/icon16.png"
    }
  },
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "content_security_policy": "script-src 'self'; object-src 'self';",
  "browser_specific_settings": {
    "gecko": {
      "id": "{f2947ea6-d189-42ca-9986-e85cd215d70e}"
    }
  }
}