UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/59.0.3071.115 Safari/537.36

Example URL:

Steps to reproduce the problem:
1. 
Visit chrome://settings/content/microphone, confirm the default is "Ask".

2.
Load an extension that will block access to your microphone on "<all_urls>" primaryPattern, eg: 

chrome.contentSettings.microphone.set({setting: "block", scope: "regular", primaryPattern: "<all_urls>"}).

3.

with the extension loaded and the above content setting rule applied, visit chrome://settings/content/microphone again. You should see the default rule is "Blocked" and that an extension is controlling the setting. All good.

4.

Call chrome.contentSettings.microphone.clear({scope: "regular"}). 

5.

Visit chrome://settings/content/microphone again.

6.

Observe that the extension is no longer controlling the setting, but the default has been changed to "Block" ! (from "Ask"). Step 3 is what causes this to happen.

What is the expected behavior?
Expected behaviour is while visiting a content setting page such as chrome://settings/content/microphone with an extension blocking access on "<all_urls>", the global browser default should not be changed to "Blocked" once an extension releases control using clear(). It should be restored to "Ask" or the users prior default.

What went wrong?
Explained in step 6 of reproduction steps.

Does it occur on multiple sites: Yes

Is it a problem with a plugin? No 

Did this work before? N/A 

Does this work in other browsers? Yes

Chrome version: 59.0.3071.115  Channel: stable
OS Version: OS X 10.11.6
Flash Version: 

Bizarre bug that took me a while to hunt down. I can see extension authors taking flake or blame for this bug from end-users of extensions.