ozone: evdev: Add a couple more trace events

Add trace event inside each read notification for evdev.

BUG=none
TEST=chrome://tracing in link_freon

Review URL: https://codereview.chromium.org/1110693003

Cr-Commit-Position: refs/heads/master@{#327110}
void TouchEventConverterEvdev::ReleaseTouches() {
  for (size_t slot = 0; slot < events_.size(); slot++)
    UpdateTrackingId(slot, kTrackingIdForUnusedSlot);

  ReportEvents(EventTimeForNow());
}

void TouchEventConverterEvdev::ReleaseTouches() {
  for (size_t slot = 0; slot < events_.size(); slot++)
    UpdateTrackingId(slot, kTrackingIdForUnusedSlot);

  ReportEvents(EventTimeForNow());
}
