Button for Dropbox™ in Gmail™

manifest.json

{
  "background": {
    "persistent": false,
    "scripts": [
      "constants.js",
      "util.js",
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "css": [
        "onboarding.css"
      ],
      "js": [
        "inboxsdk.js",
        "constants.js",
        "sha1.js",
        "util.js",
        "content.js"
      ],
      "matches": [
        "https://mail.google.com/*",
        "https://inbox.google.com/*"
      ],
      "run_at": "document_end"
    },
    {
      "js": [
        "isinstalled.js"
      ],
      "matches": [
        "https://www.dropbox.com/gmail_integration"
      ],
      "run_at": "document_end"
    }
  ],
  "default_locale": "en",
  "description": "__MSG_description__",
  "icons": {
    "16": "images/icon16.png",
    "48": "images/icon48.png",
    "128": "images/icon128.png"
  },
  "manifest_version": 2,
  "name": "__MSG_name__",
  "permissions": [
    "https://mail.google.com/*",
    "https://inbox.google.com/*",
    "storage",
    "tabs"
  ],
  "short_name": "__MSG_short_name__",
  "update_url": "https://clients2.google.com/service/update2/crx",
  "version": "1.0",
  "web_accessible_resources": [
    "images/logo.png",
    "images/icon16.png",
    "images/icon48.png",
    "images/icon128.png",
    "images/white_icon48.png",
    "images/checkmark.png",
    "images/x.png",
    "blank.html"
  ]
}