Use another file and field for wakeups count

On some Linux systems (like Ubuntu 14.04.5 or Ubuntu 16.04) with
4.8.0-49-generic kernel there's no /proc/<pid>/sched file. Or it exists
but doesn't have the required se.statistics.nr_wakeups field.
This causes TaskManagerBrowserTest.IdleWakeups test to fail and in
Chrome Task Manager all the Idle Wakeups counts are 0.

After some research I found out that the voluntary_ctxt_switches field
in file /proc/<pid>/status is practically the same as the previous
one. Using that field helps the test to pass.

BUG=717863

Review-Url: https://codereview.chromium.org/2859763002
Cr-Commit-Position: refs/heads/master@{#469270}


CrOS-Libchrome-Original-Commit: 93c0968c8188befdaeaf1d49a98ad9086fa4a0f3
1 file changed
tree: 66f685626c9bee96717817c1e2e035aef6c0da3a
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/