Open the Chrome Devtool by clicking on the background page of an extension in Chrome://extensions/ (Developer mode needs to be checked to see background pages), then in resource panel you can see the local storage on the left.
I will proceed to amalgamate the existing knowledge present in several answers, into a simple and comprehensive one. If you vote up this one, please do the same with the ones from @mwkwok and @chaohuang.
It is true that stuff saved using chrome.storage does not show up in developer tools, there you can only see stuff saved using regular localStorage API. Do this:
Open your extension's background page by going to chrome://extensions/ ("Developer mode" needs to be checked to see background pages)
I didn't get any results using the provided code typed into console. But this code worked when put into the console.
chrome.storage.sync.get(null, function (data) { console.info(data) });
The difference here is that we pass a null value which will return all content in the storage. To back this up, and for additional reading, check out the official chrome page on this API.
How do I view localStorage of a Chrome Extension I've installed?
Open the Chrome Devtool by clicking on the background page of an extension in Chrome://extensions/ (Developer mode needs to be checked to see background pages), then in resource panel you can see the local storage on the left. (by chaohuang and Kil)
How do I view chrome.storage of a Chrome Extension I've installed?
In the same console of the background page:
OPEN THE BACKGROUND PAGE FIRST:
a. to go to chrome://extensions/
b. ensure you are in development mode
c. then on your extension, either click "Inspect views background page" or go to "Details" and click background page.
NOW THAT YOU ARE ON THE BACKGROUND PAGE YOU CAN PROCEED:
In 2022, the best way I've found is still with the console.log, but you can make it a lot cleaner-looking with currying. Open up extensions page, open the inspector for your background worker, go to console, and...