Examine source code of Inbox in Gmail

{
  "name": "Inbox Reborn theme for Gmail™",
  "version": "0.5.0",
  "manifest_version": 2,
  "description": "Adds features like reminders, email bundling and Inbox's minimalistic style to Gmail™",
  "homepage_url": "https://github.com/boukestam/inbox-in-gmail",
  "browser_action": {
    "default_popup": "src/options/options.html"
  },
  "options_ui": {
    "page": "src/options/options.html",
    "open_in_tab": false
  },
  "background": {
    "scripts": [
      "src/background.js"
    ],
    "persistent": false
  },
  "permissions": [
    "storage"
  ],
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://mail.google.com/*"
      ],
      "css": [
        "src/style.css"
      ],
      "js": [
        "src/script.js"
      ],
      "run_at": "document_start"
    }
  ],
  "web_accessible_resources": [
    "images/*"
  ]
}