ccameron@, do you know if we can get the input device information from NSEvent? Thank you.

Based on the NSEvent docs, it looks like you just need to read the pointingDeviceType.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/74a646d254f3836d7df802857b5a926adc4ec87b

commit 74a646d254f3836d7df802857b5a926adc4ec87b
Author: lanwei <lanwei@chromium.org>
Date: Wed Jun 08 19:16:55 2016

We did not set the pointer type for WebMouseEvent, which is created from NSEvent in
WebMouseEventBuilder::Build. Now we set the pointer type based on the NSEvent's
type to see if it is a tablet event or subtype of a mouse event to see its input device.

Reference:
https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/EventOverview/EventObjectsTypes/EventObjectsTypes.html#//apple_ref/doc/uid/10000060i-CH4-SW4

BUG= 615122 

Review-Url: https://codereview.chromium.org/2022843002
Cr-Commit-Position: refs/heads/master@{#398635}

[modify] https://crrev.com/74a646d254f3836d7df802857b5a926adc4ec87b/content/browser/renderer_host/input/web_input_event_builders_mac.mm

Your change meets the bar and is auto-approved for M52 (branch: 2743)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f069916c1f350baa4b7f6f2c6b3d9236aa1bdb94

commit f069916c1f350baa4b7f6f2c6b3d9236aa1bdb94
Author: lanwei <lanwei@chromium.org>
Date: Thu Jun 09 22:16:06 2016

We did not set the pointer type for WebMouseEvent, which is created from NSEvent in WebMouseEventBuilder::Build. Now we set the pointer type based on the NSEvent's type to see if it is a tablet event or subtype of a mouse event to see its input device.

Reference:
https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/EventOverview/EventObjectsTypes/EventObjectsTypes.html#//apple_ref/doc/uid/10000060i-CH4-SW4

BUG= 615122 

Review-Url: https://codereview.chromium.org/2022843002
Cr-Commit-Position: refs/heads/master@{#398635}
(cherry picked from commit 74a646d254f3836d7df802857b5a926adc4ec87b)

Review URL: https://codereview.chromium.org/2056053002 .

Cr-Commit-Position: refs/branch-heads/2743@{#302}
Cr-Branched-From: 2b3ae3b8090361f8af5a611712fc1a5ab2de53cb-refs/heads/master@{#394939}

[modify] https://crrev.com/f069916c1f350baa4b7f6f2c6b3d9236aa1bdb94/content/browser/renderer_host/input/web_input_event_builders_mac.mm

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f069916c1f350baa4b7f6f2c6b3d9236aa1bdb94

commit f069916c1f350baa4b7f6f2c6b3d9236aa1bdb94
Author: lanwei <lanwei@chromium.org>
Date: Thu Jun 09 22:16:06 2016

We did not set the pointer type for WebMouseEvent, which is created from NSEvent in WebMouseEventBuilder::Build. Now we set the pointer type based on the NSEvent's type to see if it is a tablet event or subtype of a mouse event to see its input device.

Reference:
https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/EventOverview/EventObjectsTypes/EventObjectsTypes.html#//apple_ref/doc/uid/10000060i-CH4-SW4

BUG= 615122 

Review-Url: https://codereview.chromium.org/2022843002
Cr-Commit-Position: refs/heads/master@{#398635}
(cherry picked from commit 74a646d254f3836d7df802857b5a926adc4ec87b)

Review URL: https://codereview.chromium.org/2056053002 .

Cr-Commit-Position: refs/branch-heads/2743@{#302}
Cr-Branched-From: 2b3ae3b8090361f8af5a611712fc1a5ab2de53cb-refs/heads/master@{#394939}

[modify] https://crrev.com/f069916c1f350baa4b7f6f2c6b3d9236aa1bdb94/content/browser/renderer_host/input/web_input_event_builders_mac.mm

lanwei@, can you please let us know if this can be tested manually ?

Yes, please use this page http://rbyers.github.io/eventTest.html and choose only pointer in the config list on the top left. When you test, please enable Pointer Events Mac, Windows, Linux, Chrome OS, Android on the chrome://flags. Please check with mouse and a stylus device.