histograms.xml: add ProcessMemory histograms

These histograms collect memory usage information for processes,
classified into six groups (browser, GPU, renderers, ARC++, VMs
and daemons) and five usage types (total, anonymous, file, shmem,
and swap).

BUG=chromium:957990
TEST=none

Change-Id: Ib2b7519bbc0f2f8eb09c5e7bb0da31dac1914494
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1613738
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Commit-Queue: Luigi Semenzato <semenzato@chromium.org>
Auto-Submit: Luigi Semenzato <semenzato@chromium.org>
Cr-Commit-Position: refs/heads/master@{#661547}
1 file changed