Before:
https://htmlpreview.github.io/?https://raw.githubusercontent.com/WebAudio/web-midi-api/549d2a34e595fc100ea9fad20c17e6ebb2122ac7/index.html#MIDIMessageEvent

After:
http://webaudio.github.io/web-midi-api/#MIDIMessageEvent

Now the spec was updated.

Plan:
M-53: Show a deprecate message.
M-54: Remove receivedTime attribute.

https://www.chromestatus.com/features/5665772797952000

Intent to Deprecate
https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/zOMo62KH8ns

Create a relevant thread at WG to consider merge MIDIMessageEvent to another existing one; https://github.com/WebAudio/web-midi-api/issues/165

deprecation is slipped to m54. Also as discussed at blink-dev, I'll remove it after waiting one more milestone. That means I'll remove at m56.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b253a5c54917c2f7bd96f1acf2eeb7d3014a9288

commit b253a5c54917c2f7bd96f1acf2eeb7d3014a9288
Author: toyoshim <toyoshim@chromium.org>
Date: Tue Jul 05 09:03:11 2016

Web MIDI: prepare to deprecate MIDIMessageEvent::receivedTime

Now that Event::timeStamp is equivalent to DOMHighResTimeStamp,
WG decided to drop DOMHighResTimeStamp receivedTime attribute
from MIDIMessageEvent.

Our plan is to show a deprecate message on M54, then remove it
completely on M56.

This patch changes to show a deprecate message when JavaScript
touches the receivedTime attribute.

BUG= 599335 

Review-Url: https://codereview.chromium.org/2099213002
Cr-Commit-Position: refs/heads/master@{#403756}

[modify] https://crrev.com/b253a5c54917c2f7bd96f1acf2eeb7d3014a9288/third_party/WebKit/LayoutTests/fast/events/constructors/midi-message-event-constructor-expected.txt
[modify] https://crrev.com/b253a5c54917c2f7bd96f1acf2eeb7d3014a9288/third_party/WebKit/LayoutTests/webmidi/loopback-receive-expected.txt
[modify] https://crrev.com/b253a5c54917c2f7bd96f1acf2eeb7d3014a9288/third_party/WebKit/LayoutTests/webmidi/loopback-receive.html
[modify] https://crrev.com/b253a5c54917c2f7bd96f1acf2eeb7d3014a9288/third_party/WebKit/Source/core/frame/Deprecation.cpp
[modify] https://crrev.com/b253a5c54917c2f7bd96f1acf2eeb7d3014a9288/third_party/WebKit/Source/core/frame/UseCounter.h
[modify] https://crrev.com/b253a5c54917c2f7bd96f1acf2eeb7d3014a9288/third_party/WebKit/Source/modules/webmidi/MIDIMessageEvent.cpp
[modify] https://crrev.com/b253a5c54917c2f7bd96f1acf2eeb7d3014a9288/third_party/WebKit/Source/modules/webmidi/MIDIMessageEvent.h
[modify] https://crrev.com/b253a5c54917c2f7bd96f1acf2eeb7d3014a9288/third_party/WebKit/Source/modules/webmidi/MIDIMessageEvent.idl
[modify] https://crrev.com/b253a5c54917c2f7bd96f1acf2eeb7d3014a9288/tools/metrics/histograms/histograms.xml

changed status to wait for removing it at m56.

The M56 branch point is a couple weeks away and I see a removal warning in Deprecation.cpp, so checking in to see if this is on track for removal in M56?

Sorry, I just forgot about this.
I will send a Intent to Remove right now.

I'm not sure if I need to take Launch-OWP review for this, but I'd change the type to Launch-OWP because the mail template has a filed for Launch-OWP bug.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/78d9022f114359c780331d9a6e8a34ce8cdbf6fa

commit 78d9022f114359c780331d9a6e8a34ce8cdbf6fa
Author: toyoshim <toyoshim@chromium.org>
Date: Mon Nov 14 08:42:22 2016

Web MIDI: deprecate MIDIMessageEvent.receivedTime

As we planned, drop MIDIMessageEvent.receivedTime support from Web MIDI.
This is because Event can provide timeStamp in HighResTimeStamp today.

https://groups.google.com/a/chromium.org/d/topic/blink-dev/sT4M99V29SE/discussion

BUG= 599335 

Review-Url: https://codereview.chromium.org/2489033005
Cr-Commit-Position: refs/heads/master@{#431843}

[modify] https://crrev.com/78d9022f114359c780331d9a6e8a34ce8cdbf6fa/third_party/WebKit/LayoutTests/fast/events/constructors/midi-message-event-constructor-expected.txt
[modify] https://crrev.com/78d9022f114359c780331d9a6e8a34ce8cdbf6fa/third_party/WebKit/LayoutTests/fast/events/constructors/midi-message-event-constructor.html
[modify] https://crrev.com/78d9022f114359c780331d9a6e8a34ce8cdbf6fa/third_party/WebKit/LayoutTests/platform/linux/virtual/stable/webexposed/global-interface-listing-expected.txt
[modify] https://crrev.com/78d9022f114359c780331d9a6e8a34ce8cdbf6fa/third_party/WebKit/LayoutTests/platform/win/virtual/stable/webexposed/global-interface-listing-expected.txt
[modify] https://crrev.com/78d9022f114359c780331d9a6e8a34ce8cdbf6fa/third_party/WebKit/LayoutTests/virtual/stable/webexposed/global-interface-listing-expected.txt
[modify] https://crrev.com/78d9022f114359c780331d9a6e8a34ce8cdbf6fa/third_party/WebKit/LayoutTests/webexposed/global-interface-listing-expected.txt
[modify] https://crrev.com/78d9022f114359c780331d9a6e8a34ce8cdbf6fa/third_party/WebKit/LayoutTests/webmidi/loopback-receive-expected.txt
[modify] https://crrev.com/78d9022f114359c780331d9a6e8a34ce8cdbf6fa/third_party/WebKit/LayoutTests/webmidi/loopback-receive.html
[modify] https://crrev.com/78d9022f114359c780331d9a6e8a34ce8cdbf6fa/third_party/WebKit/Source/core/frame/Deprecation.cpp
[modify] https://crrev.com/78d9022f114359c780331d9a6e8a34ce8cdbf6fa/third_party/WebKit/Source/modules/webmidi/MIDIAccess.cpp
[modify] https://crrev.com/78d9022f114359c780331d9a6e8a34ce8cdbf6fa/third_party/WebKit/Source/modules/webmidi/MIDIMessageEvent.cpp
[modify] https://crrev.com/78d9022f114359c780331d9a6e8a34ce8cdbf6fa/third_party/WebKit/Source/modules/webmidi/MIDIMessageEvent.h
[modify] https://crrev.com/78d9022f114359c780331d9a6e8a34ce8cdbf6fa/third_party/WebKit/Source/modules/webmidi/MIDIMessageEvent.idl
[modify] https://crrev.com/78d9022f114359c780331d9a6e8a34ce8cdbf6fa/third_party/WebKit/Source/modules/webmidi/MIDIMessageEventInit.idl