Snail on Gmail Loading Page

manifest.json

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "name": "Snail on Gmail Loading Page",
  "short_name": "Snail Gmail",
  "description": "We noticed that new Gmail is loading like a snail. Let's watch the crawling snail while it is loading! It's funny, raise your mood!",
  "version": "1.0",
  "homepage_url": "https://yuragalin.com/it/snail-gmail",
  "permissions": [
    "storage",
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "favicon1.png",
    "default_title": "Snail Gmail",
    "default_popup": "popup.html"
  },
  "manifest_version": 2,
  "content_scripts": [
    {
      "matches": [
        "https://mail.google.com/*"
      ],
      "all_frames": true,
      "js": [
        "scripts/content.js"
      ]
    }
  ],
  "web_accessible_resources": [
    "snail-animation.gif"
  ]
}