GitLab

When collecting upon resume from suspend or session restore, don't always
collect right away. Introduce a random delay before collecting.

BUG=chromium:358778
TEST=Do the following:
- Add logging to ParseProtoIfValid().
- Set kResumeSamplingFactor=1 and kRestoreSessionSamplingFactor=1. This makes
  collection happen 100% of the time.
- Set kPerfProfilingIntervalMs=20000. This makes the periodic collection happen once every 20-second interval.
- Trigger both types of collections, resume and restore:
  = Suspend and resume the system.
  = Open some tabs in ChromeOS, log out of Chrome, and then log back in so that
    the session is restored.
- Should see the logging trace displayed in /var/log/ui/ui.LATEST after a
  random delay.
- Should also see the periodic collections take place.
  = Open an incognito window. It should continue to attempt to collect. (Add a trace to ScheduleIntervalCollection to see that this is the case).
Signed-off-by: Simon Que <sque@chromium.org>

Review URL: https://codereview.chromium.org/364913007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@283674 0039d316-1c4b-4281-b951-d872f2087c98