Implementation in progress in https://codereview.chromium.org/1765533004/. First, I need to land puch / cancelPush functionality https://codereview.chromium.org/1486043002

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/55ac6a4ca3780a5c315a7014f43642e43c5245f0

commit 55ac6a4ca3780a5c315a7014f43642e43c5245f0
Author: alexander.shalamov <alexander.shalamov@intel.com>
Date: Wed Nov 30 09:04:17 2016

[webnfc] Implement watch method for Android nfc mojo service.

Implementation of nfc.watch [1] and nfc.cancelWatch [2] methods
for Android nfc mojo service that is used from W3C WebNFC module.

[1] https://w3c.github.io/web-nfc/#dom-nfc-watch
[2] https://w3c.github.io/web-nfc/#dom-nfc-cancelwatch

BUG=520391
BUG= 625589 

Review-Url: https://codereview.chromium.org/1765533004
Cr-Commit-Position: refs/heads/master@{#435189}

[modify] https://crrev.com/55ac6a4ca3780a5c315a7014f43642e43c5245f0/device/BUILD.gn
[modify] https://crrev.com/55ac6a4ca3780a5c315a7014f43642e43c5245f0/device/nfc/android/BUILD.gn
[modify] https://crrev.com/55ac6a4ca3780a5c315a7014f43642e43c5245f0/device/nfc/android/java/src/org/chromium/device/nfc/NfcImpl.java
[add] https://crrev.com/55ac6a4ca3780a5c315a7014f43642e43c5245f0/device/nfc/android/java/src/org/chromium/device/nfc/NfcMessageValidator.java
[modify] https://crrev.com/55ac6a4ca3780a5c315a7014f43642e43c5245f0/device/nfc/android/java/src/org/chromium/device/nfc/NfcTagHandler.java
[modify] https://crrev.com/55ac6a4ca3780a5c315a7014f43642e43c5245f0/device/nfc/android/java/src/org/chromium/device/nfc/NfcTypeConverter.java
[add] https://crrev.com/55ac6a4ca3780a5c315a7014f43642e43c5245f0/device/nfc/android/junit/src/org/chromium/device/nfc/NFCTest.java

This issue has been Available for over a year. If it's no longer important or seems unlikely to be fixed, please consider closing it out. If it is important, please re-triage the issue.

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