UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/59.0.3071.86 Safari/537.36

Steps to reproduce the problem:
1. Open test page served from local server (e.g. not open file directly)
2. Open dev tools network tab
3. Make sure "Disable cache" is not checked (e.g. cache is functional)
4. Refresh the page multiple times to make XHR request* multiple times

* XHR request makes HEAD request to https://httpbin.org/cache which in turn returns response with "Last-Modified" header.

In case test file does not work XHR request is very simple:

var xhr = new XMLHttpRequest();
xhr.open("HEAD", 'https://httpbin.org/cache', true);
xhr.send();

What is the expected behavior?
After first fetch of the resource, subsequent requests should be sending "If-Modified-Since" header in which case server can return 304 Not Modified response.

In other browsers (tested in Firefox and Safari) it works as expected and non-first requests indeed return 304 responses.

What went wrong?
Chrome does not send "If-Modified-Since" header hence server is always returning 200 OK response.

Note that Chrome honors cache for GET requests. This behavior seems only to be present for HEAD requests.

Did this work before? N/A 

Does this work in other browsers? Yes

Chrome version: 59.0.3071.86  Channel: stable
OS Version: OS X 10.10.5
Flash Version: 

https://httpbin.org/cache does not seem to return Cache-Control header so in my local server I also was returning "Cache-Control: private, must-revalidate, max-age=3600" header which did not affect XHR HEAD requests caching in any way.
 

Deleted: cache-test.html 279 bytes

cache-test.html 279 bytes View Download