Kevin's going to try and build-bisect this, just needs to find a non-CrOS machine with a touch screen ...

Pinch zooming on Windows canary (58.0.3022.0) still works.

So this looks like it's platform specific as pinch zooming is broken on 58.0.3022.0 for chrome os.

rev 66847e854d3a is good on chrome os, although I get the following DCHECK for some sites:
[1:1:0224/143422.863913:FATAL:PointerEventFactory.cpp(326)] Check failed: touchPoint.state == coalescedTouchPoint.state (3 vs. 4)

rev 2db168c3d25f is bad.

I'll see if I can narrow it down some more.

This was broken in crrev.com/31739e48ae97 (Add id properties to PointerEvent)

I commented out a suspect line in the CL: I think we are not using the value GetTouchId(native_event) now in TouchEvent(NativeEvent&) constructor.

This also seems to break multi-touch and stylus support for ARC++: https://bugs.chromium.org/p/chromium/issues/detail?id=696369

Dave, are you looking into this? I am not very familiar with this part of the code. 

I am looking at it right now.

Sorry, I was referring to the touch screen pinch zoom being broken.

disregard my comment (i've deleted it)

I believe the problematic code is here: https://cs.chromium.org/chromium/src/ui/events/ozone/evdev/event_factory_evdev.cc?dr=CSs&q=event_factory&l=345

Lan can you prepare a patch to fix this and test out the other scenarios?

Some reports in Chromebook Central:
https://productforums.google.com/forum/#!topicsearchin/chromebook-central/r11$20Pinch$20to$20zoom

#CBC-RS/TC-watchlist

I have a CL ready, it is under review now.
https://codereview.chromium.org/2720133002/

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/de104fb57e491bef3f2883f5a9100b9524fb0e3c

commit de104fb57e491bef3f2883f5a9100b9524fb0e3c
Author: lanwei <lanwei@chromium.org>
Date: Thu Mar 02 21:22:49 2017

Make pinch zoom work on chromeos by setting touch id correctly

In EventFactoryEvdev, the touch id is reset to default value 0 after setting a PointerDetails object,
which causes two touch pointer have the same id, and pinch zoom does not work.

We need to set the touch id in PointerDetails and check in all the set_pointer_details
to make sure that id is not reset to default.

BUG= 695905 , 696369 

Review-Url: https://codereview.chromium.org/2720133002
Cr-Commit-Position: refs/heads/master@{#454378}

[modify] https://crrev.com/de104fb57e491bef3f2883f5a9100b9524fb0e3c/ui/events/event.cc
[modify] https://crrev.com/de104fb57e491bef3f2883f5a9100b9524fb0e3c/ui/events/event.h
[modify] https://crrev.com/de104fb57e491bef3f2883f5a9100b9524fb0e3c/ui/events/event_unittest.cc
[modify] https://crrev.com/de104fb57e491bef3f2883f5a9100b9524fb0e3c/ui/events/ozone/evdev/event_factory_evdev.cc

 Issue 698558  has been merged into this issue.