UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.94 Safari/537.36

Steps to reproduce the problem:
1. Add a 'touchstart' event listener to the window.
2. Add a 'scroll' event listener to the window.
3. In 'scroll' listener callback use requestIdleCallback to invoke some function, let's call it 'foo'.
4. Scroll a bit and stop (you can use mouse or finger but not keyboard).
5. 'foo' is called after 2000ms

What is the expected behavior?
5. 'foo' is called immediately (less than ~50ms)

What went wrong?
Even though the CPU is completly idle, 'foo' is called after a long time. AFAIR 2000ms is the default timeout for RIC in Chrome.

Did this work before? N/A 

Does this work in other browsers? Yes

Chrome version: 62.0.3202.94  Channel: stable
OS Version: OS X 10.13.1
Flash Version: 

Here's a sample code: https://jsfiddle.net/wgvbfz8n/4/ Output is like (top is more recent):

Waited 2003ms
Waited 2019ms
Waited 2036ms
Waited 16ms
Waited 34ms

I see no reason why Chrome should wait this long, especially on desktop, where the touchstart is not even fired. This hurts the performance of scroll-dependant features and libraries (such as "lazysizes") which use RIC internally. You can override the timeout https://github.com/aFarkas/lazysizes/issues/434 but it's just a workaround.

Actually 'scroll' listener is unrelated, if you invoke requestIdleCallback in a loop, then adding 'touchstart' listener still affects when the callbacks are called.
Scrolling with a keyboard (i.e. down arrow) works fine.
Doesn't work on Android (Chrome 62).