Today, when tab manager gets a critical memory pressure signal, we still shut down the tab gracefully. This is bad for the user: it is important to respond to critical pressure signals rapidly, so the OS doesn't have to go killing processes itself. Doing a graceful shutdown of a tab involves running potentially large amounts of JS, which may in turn allocate memory, or trigger page faults to bring in the page's memory that would have otherwise been swapped out to save memory. Combined, this behavior ends up making a critical-memory situation worse, not better.

Expected behavior: chrome responds as rapidly as possible to critical memory pressures situations.