Document how raised touches should be reported

It wasn't immediately clear before whether a raised touch should be
reported one last time with tracking_id = -1 in its FingerState, or just
dropped from the fingers array altogether. It turns out to be the latter
[0], so add some comments to make that clear.

Also move the information from a comment that had somehow been separated
from the FingerState struct, while we're at it.

[0]: https://crsrc.org/c/ui/events/ozone/evdev/libgestures_glue/gesture_interpreter_libevdev_cros.cc;l=199;drc=3e1a26c44c024d97dc9a4c09bbc6a2365398ca2c

BUG=None
TEST=emerge-volteer chromeos-base/gestures

Change-Id: I8325a1b9bfedaa88c9a5d15a85d1b7d1b3498e59
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/gestures/+/4360158
Tested-by: Harry Cutts <hcutts@chromium.org>
Auto-Submit: Harry Cutts <hcutts@chromium.org>
Reviewed-by: Torsha Banerjee <torsha@google.com>
Code-Coverage: Torsha Banerjee <torsha@google.com>
Reviewed-by: Sean O'Brien <seobrien@chromium.org>
Commit-Queue: Harry Cutts <hcutts@chromium.org>
1 file changed