How do I implement a tip jar in a Chrome extension?

I have created a Chrome extension that I would like to give away for free, but provide a "tip jar" on the extension's options page where people can, if they want, opt send me a small amount of money to show their appreciation. I've looked through the documentation for one-time payments and Google Wallet for Digital Goods, but nothing I see there seems like a fit. It seems like the only options listed are:

1. Free extension, no payment mechanism: Not desirable because I want to offer people the option to pay something.
2. Paid extension: No, I want it to be free.
3. Free trial: This will make people think that the extension is limited in some fashion unless they pay, which it isn't.
4. In-app purchases: Same as above. I'd rather that my extension not be marked as having in-app purchases, since there is no limitation that you have to pay to remove, and the only thing paying gets you is good karma.

Is there a built-in Chrome Web Store option that is suitable for what I'm trying to do? If not, can Google Wallet be leveraged in some way to provide "tip jar" functionality, or will I have to find some other payment mechanism?

A lot of developers implement voluntary tips via PayPal donation buttons.

One could simply add the button to their options page. E.g.: [1] [2]

Cautionary tale: PayPal can, in principle, throw a hissy fit over collected funds, but as long as you don't rake in thousands you should be okay.

Please note: Fundraisers that are not verified nonprofits will be asked to demonstrate how their donations will be used, once they raise more than $10,000

Patreon is currently gaining popularity. I know at least one extension (Enhanced Steam) that went that route.