This looks like the radius is coming directly from the driver.

tbuckley@ can you triage?

The driver does not report touch_major (which will later be radius_x, then height) for stylus. Until ozone events is dispatched, the radius_x is still 0.

But in blink code, the WebTouchEvent radius_x is set to 25.
I would assume somewhere along the dispatch patch, the value is set to 25 when the radius_x is 0. 

Could you take a look? dtapuska@

jkwang@ I do agree the driver is reporting no width/height. Why can't the driver 
report this value even for touch events? 

Aura is filing it in here:
https://cs.chromium.org/chromium/src/ui/events/gestures/motion_event_aura.cc?dr=CSs&l=46

and it seems wrong to do it for touch events no?

It should be OK for touch events if it's a finger. When the screen is not able to report a major, the assumptions here is not bad.

And I think it makes sense that the stylus driver does not report width/height, because the contact of stylus is the pen tip.

I would suggest check the EventPointerType here and put a different default for POINTER_TYPE_PEN. You could well assume the width/height of stylus is 1mm.

With that said, I am not sure if what is expected by the consumer of touch events (in the user level). If any of them requires a contact size to trigger some events, this change will disable stylus. Say, if I require a minimum contact size of 5 mm to press down my button, stylus could not do it after this change. Please do take this into your consideration.

jkwang@ I'm trying eve and touch_major/minor isn't reported for fingers either.

I agree I will make 1x1 the default for types pen/eraser.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e2f1551a57b8ac6e144582fdb6879552be6ae288

commit e2f1551a57b8ac6e144582fdb6879552be6ae288
Author: Dave Tapuska <dtapuska@chromium.org>
Date: Tue Oct 24 01:18:56 2017

Fix default size for pointer stylus events on aura.

If the radius_x/y wasn't provided on the native event the field would
get populated by the gesture code. For stylus events it should be
a 1x1 pixel point as opposed to the 50x50 circle that is the default
in the GestureConfig.

BUG= 773262 

Change-Id: I5124ecf43bb592a1b3e3ccbbdb7c09020f79bbdd
Reviewed-on: https://chromium-review.googlesource.com/734016
Reviewed-by: Timothy Dresser <tdresser@chromium.org>
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Cr-Commit-Position: refs/heads/master@{#510980}
[modify] https://crrev.com/e2f1551a57b8ac6e144582fdb6879552be6ae288/ui/events/gestures/motion_event_aura.cc
[modify] https://crrev.com/e2f1551a57b8ac6e144582fdb6879552be6ae288/ui/events/gestures/motion_event_aura_unittest.cc