Suspected cl:
https://chromium-review.googlesource.com/c/chromium/src/+/722442

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/3627230aca1ff87baf2b3ab2ca3057f4dce361eb

commit 3627230aca1ff87baf2b3ab2ca3057f4dce361eb
Author: Daniel Murphy <dmurph@chromium.org>
Date: Tue Oct 17 19:13:05 2017

Revert "Allow Chrome on Mac to recognize multiple MFi gamepads"

This reverts commit d81a48d91c135c6a294a7fbf4a29217b438e8c47.

Reason for revert: failing mac builders
Bug:  775614 

Original change's description:
> Allow Chrome on Mac to recognize multiple MFi gamepads
> 
> Chrome for Mac recognizes "Made for iOS" (MFi) gamepads enumerated
> by the GameController framework. When multiple such devices are
> connected at once, Chrome fails to properly distinguish them.
> 
> GCController exposes a playerIndex field that defaults to the value
> GCControllerPlayerIndexUnset (-1). The application may set this field
> to a value between 0 and 3 to signal which LEDs should be lit on the
> gamepad. Chrome also uses this field to distinguish gamepads, but does
> not set the index to a unique value. This causes the first-connected
> gamepad to shadow any other connected gamepads.
> 
> This CL ensures each connected MFi gamepad is assigned a unique player
> index up to the OS-defined limit of four.
> 
> BUG= 775270 
> 
> Change-Id: Ic60efe4a660f3d6c9ca2f840d059f23c78a6fa6c
> Reviewed-on: https://chromium-review.googlesource.com/722442
> Reviewed-by: Brandon Jones <bajones@chromium.org>
> Commit-Queue: Matt Reynolds <mattreynolds@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#509464}

TBR=bajones@chromium.org,mattreynolds@chromium.org

Change-Id: I4351f37277bf939055d3d1b0b123a3f9400c9043
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug:  775270 
Reviewed-on: https://chromium-review.googlesource.com/723805
Reviewed-by: Daniel Murphy <dmurph@chromium.org>
Commit-Queue: Daniel Murphy <dmurph@chromium.org>
Cr-Commit-Position: refs/heads/master@{#509474}
[modify] https://crrev.com/3627230aca1ff87baf2b3ab2ca3057f4dce361eb/device/gamepad/game_controller_data_fetcher_mac.h
[modify] https://crrev.com/3627230aca1ff87baf2b3ab2ca3057f4dce361eb/device/gamepad/game_controller_data_fetcher_mac.mm