Sync XHR in Window context is terrible, and if just possible we should get rid of it. (it may takes years to achieve that)
Created attachment 575543 [details] [diff] [review] patch
Comment on attachment 575543 [details] [diff] [review] patch Assuming this will let us see how man async as well as sync requests are made. It'd be awesome if we could get a count on how many sites out there use sync XHR, but I don't see a way of doing that without effectively sending the domain name of the site to us, which would be terrible privacy.
This counts all the open() calls, and either increases the async bar (0), or sync bar(1), so yes it is easy to check how many XHR open calls there has been, and how many of those have been sync.
Comment on attachment 575543 [details] [diff] [review] patch dont need empty lines in TelemetryHistograms.h