Examine source code of Dedupe: Tab Deduplicator

{
  "manifest_version": 2,
  "name": "Dedupe: Tab Deduplicator",
  "version": "2.1",
  "description": "Switch to existing tab instead of opening duplicate",
  "permissions": [
    "storage",
    "tabs",
    "sessions"
  ],
  "icons": {
    "16": "icons/enabled/icon16.png",
    "48": "icons/enabled/icon48.png",
    "128": "icons/enabled/icon128.png"
  },
  "browser_action": {
    "default_icon": {
      "32": "icons/enabled/icon32.png",
      "64": "icons/enabled/icon64.png"
    },
    "default_popup": "popup/popup.html"
  },
  "background": {
    "scripts": [
      "background/background.js"
    ]
  },
  "commands": {
    "toggle-pause": {
      "suggested_key": {
        "default": "Shift+Alt+X"
      },
      "description": "Pause/unpause the deduplication feature"
    },
    "detach-tabs": {
      "suggested_key": {
        "default": "Ctrl+Shift+Space"
      },
      "description": "Detach selected tabs from their window and open them in a new window"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "@dedupe-tab-deduplicator",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}