The Are We Slim Yet project (commonly known as AWSY) for several years tracked memory usage across builds on the (now defunct) website areweslimyet.com. It used the same infrastructure as about:memory to measure memory usage on a predefined snapshot of Alexa top 100 pages known as tp5.
Since Firefox transitioned to using multiple processes by default, we moved AWSY into the TaskCluster infrastructure. This allowed us to run measurements on all branches and platforms. The results are posted to perfherder where we can track regressions automatically.
As new processes are added to Firefox we want to make sure their memory usage is also tracked by AWSY. To this end we request that memory reporting be integrated into any new process before it is enabled on Nightly.