Coinbase does not have a browser extension named "Coinbase Extension." However, it's important to note that new features and extensions could have been introduced since then, and I recommend checking the official Coinbase website or extension store for the most up-to-date information.

If Coinbase has indeed introduced a browser extension after my last update, you might typically set up a Coinbase wallet extension by following general steps for browser extensions. Here's a hypothetical guide on how you might set up a Coinbase Wallet extension:

1. Visit the Extension Store:   Go to the extension store of your preferred web browser (such as Chrome Web Store, Firefox Add-ons, or Microsoft Edge Add-ons).

2. Search for Coinbase Extension:   In the extension store's search bar, type "Coinbase" to search for any available Coinbase-related extensions.

3. Choose the Official Extension:   Ensure that you are selecting the official Coinbase extension, if available. Be cautious of third-party extensions and always prefer the ones provided by the official source.

4. Install the Extension:   Click on the "Install" or "Add to Chrome" (or equivalent for your browser) button to initiate the installation of the Coinbase extension.

5. Follow Setup Instructions:   Once the extension is installed, you may be prompted to follow setup instructions. This could include logging in with your Coinbase credentials or creating a new Coinbase account if you don't have one.

6. Secure Your Wallet:   If this extension functions as a wallet, you might be required to set up additional security measures, such as a PIN code, password, or biometric authentication.

7. Fund Your Wallet:   If your extension wallet is empty, you may need to transfer or deposit funds into it. Follow the instructions provided by the extension to fund your wallet with cryptocurrencies.

8. Explore Features:   Explore the features offered by the Coinbase extension. This may include viewing your wallet balance, managing transactions, and potentially interacting with decentralized applications (DApps) if the extension supports them.

9. Keep Your Extension Updated:   Regularly check for updates to the Coinbase extension. Keeping your extension up-to-date ensures that you have access to the latest features and security enhancements.

10. Be Cautious:   Exercise caution when interacting with any cryptocurrency-related extensions. Only use extensions from official sources to avoid potential security risks.

Please note that the steps outlined above are hypothetical and based on the general process for setting up browser extensions. Always refer to the official Coinbase website or extension store for the specific and accurate instructions related to any Coinbase browser extension. If there are any security-related measures, follow them diligently to ensure the safety of your cryptocurrency holdings.