The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b2ece72ff91d343164c1c23d46ac9608ecbd89e8

commit b2ece72ff91d343164c1c23d46ac9608ecbd89e8
Author: erikchen <erikchen@chromium.org>
Date: Wed Sep 06 18:33:32 2017

Implement dumping all processes with --memlog=all into tracing.

This CL adds some logic to iterate through all processes, and then request dumps
for each process. Some of these processes won't be profiling [e.g. utility
processes, including the profiling process], but that case is gracefully handled
by the profiling process.

The alternative would be to track all "profiled" processes as they are created,
and destroyed. This is possible using the BrowserChildProcessObserver and
NotificationObserver interfaces, but this adds yet another cache that holds
redundant information.

Bug:  758437 
Change-Id: I886d3a6c622320fd8a1ec59f6958193a7a32ef3e
Reviewed-on: https://chromium-review.googlesource.com/650687
Reviewed-by: Brett Wilson <brettw@chromium.org>
Commit-Queue: Erik Chen <erikchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#500017}
[modify] https://crrev.com/b2ece72ff91d343164c1c23d46ac9608ecbd89e8/chrome/browser/profiling_host/profiling_process_host.cc