||The purpose of this test it to measure the performance of a
content process startup.
In practice it measures a bit more than the content process startup. First
the parent process starts the clock and requests a new tab with a simple
page and then the child stops the clock in the frame script that will be
able to process the URL to handle. So it does measure a few things
pre process creation (browser element and tab creation on parent side) but
does not measure the part where we actually parse and render the page on
the content side, just the overhead of spawning a new content process.