The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4afd513b88234976f17b06eee24892ce9d149e7e

commit 4afd513b88234976f17b06eee24892ce9d149e7e
Author: Takashi Toyoshima <toyoshim@chromium.org>
Date: Fri Jul 14 12:58:01 2017

Web MIDI: MIDIPort::open/close should run asynchronously

Current implementation dispatch MIDIConnectionEvent synchronously,
but this should be done asynchronously according to the spec.

BUG= 735058 

Change-Id: If49d588e36e092aa6fc40625fd88483c9ae1719d
Reviewed-on: https://chromium-review.googlesource.com/545577
Commit-Queue: Takashi Toyoshima <toyoshim@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Cr-Commit-Position: refs/heads/master@{#486745}
[modify] https://crrev.com/4afd513b88234976f17b06eee24892ce9d149e7e/third_party/WebKit/LayoutTests/webmidi/implicit-open-expected.txt
[modify] https://crrev.com/4afd513b88234976f17b06eee24892ce9d149e7e/third_party/WebKit/LayoutTests/webmidi/implicit-open.html
[modify] https://crrev.com/4afd513b88234976f17b06eee24892ce9d149e7e/third_party/WebKit/LayoutTests/webmidi/state-check-utils.js
[modify] https://crrev.com/4afd513b88234976f17b06eee24892ce9d149e7e/third_party/WebKit/Source/modules/webmidi/MIDIOutput.cpp
[modify] https://crrev.com/4afd513b88234976f17b06eee24892ce9d149e7e/third_party/WebKit/Source/modules/webmidi/MIDIOutput.h
[modify] https://crrev.com/4afd513b88234976f17b06eee24892ce9d149e7e/third_party/WebKit/Source/modules/webmidi/MIDIPort.cpp
[modify] https://crrev.com/4afd513b88234976f17b06eee24892ce9d149e7e/third_party/WebKit/Source/modules/webmidi/MIDIPort.h