What is chrome browsermetrics-spare.pma ?

I noticed this in the latest version of CCleaner that it was cleaning this path.

Is this something new within Chrome or has it always been there?

Apparently it's been around for a while, this is from 2018:

https://groups.google.com/a/chromium.org/g/crashpad-dev/c/2YZHzOpeAT8

From the 3rd post there:

Quote
<div class="ipsQuote_contents ipsClearfix" data-gramm="false">
	<blockquote class="ipsQuote" data-gramm="false" data-ipsquote="">
		<div class="ipsQuote_citation">
			Quote
		</div>

		<div class="ipsQuote_contents ipsClearfix" data-gramm="false">
			<p>
				A. Browser Metrics:


				1. What is the difference between C:\Users\username\AppData\Local\Google\Chrome\User Data\BrowserMetrics\BrowserMetrics-identifier.pma and C:\Users\username\AppData\Local\Google\Chrome\User Data\BrowserMetrics-spare.pma?
			</p>
		</div>
	</blockquote>

	<p>
		The "BrowserMetrics-identifier.pma" files are the actual written-to files.  One of them is live and any others are from previous runs that we'll be deleted once any final information is retrieved from them.
	</p>

	<p>
		The "spare" file is an optimization.  it takes time to create and fully realize the file (done to minimize the possibility of disk errors while in active use) so one is created after Chrome has been running a short while.  This empty (all zeros) file will be used on the next run so as to not delay startup trying to create one.
	</p>

	<p>
		 
	</p>
</div>

Thanks. It appears to be new though for CCleaner.

I wonder if it's because how there are different "versions" of Chrome now where some systems aren't able to access individual cookies any longer and the cookies settings including site settings too. I posted this anomaly in another thread:

7 hours ago, Hmm said:
<div class="ipsQuote_contents ipsClearfix" data-gramm="false">
	<p>
		Thanks.  It appears to be new though for CCleaner.
	</p>
</div>

It could well be new cleaning, the release notes for v5.90 that was released this week do say:

Expanding our cleaning

  • Added new temp file cleaning for Chrome User Data

https://www.ccleaner.com/knowledge/ccleaner-v5-90-9443