The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/06ae32d640c8e4b86ea8914a80ee419ea16e56d8

commit 06ae32d640c8e4b86ea8914a80ee419ea16e56d8
Author: Jun Choi <hongjunchoi@chromium.org>
Date: Thu Dec 21 21:33:39 2017

Support CBOR encoding and decoding of negative integers

Added support for major type 1 for CBORValue, CBORReader, and
CBORWriter, and reduced the accepted range of major type 0 to
what fits in an int64_t. While the CBOR major types 0 and 1
together can represent integers in the range [-2^64, 2^64-1], to
reduce the C++ interface complexity we now represent them both in
an int64_t, with the range [-2^63, 2^63-1].

Bug:  786217 
Change-Id: Ifee69efcddecea104532b99176d705b3d2801f41
Reviewed-on: https://chromium-review.googlesource.com/777807
Commit-Queue: Jun Choi <hongjunchoi@chromium.org>
Reviewed-by: Balazs Engedy <engedy@chromium.org>
Reviewed-by: Jeffrey Yasskin <jyasskin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#525809}
[modify] https://crrev.com/06ae32d640c8e4b86ea8914a80ee419ea16e56d8/content/browser/webauth/cbor/cbor_reader.cc
[modify] https://crrev.com/06ae32d640c8e4b86ea8914a80ee419ea16e56d8/content/browser/webauth/cbor/cbor_reader.h
[modify] https://crrev.com/06ae32d640c8e4b86ea8914a80ee419ea16e56d8/content/browser/webauth/cbor/cbor_reader_unittest.cc
[modify] https://crrev.com/06ae32d640c8e4b86ea8914a80ee419ea16e56d8/content/browser/webauth/cbor/cbor_values.cc
[modify] https://crrev.com/06ae32d640c8e4b86ea8914a80ee419ea16e56d8/content/browser/webauth/cbor/cbor_values.h
[modify] https://crrev.com/06ae32d640c8e4b86ea8914a80ee419ea16e56d8/content/browser/webauth/cbor/cbor_values_unittest.cc
[modify] https://crrev.com/06ae32d640c8e4b86ea8914a80ee419ea16e56d8/content/browser/webauth/cbor/cbor_writer.cc
[modify] https://crrev.com/06ae32d640c8e4b86ea8914a80ee419ea16e56d8/content/browser/webauth/cbor/cbor_writer.h
[modify] https://crrev.com/06ae32d640c8e4b86ea8914a80ee419ea16e56d8/content/browser/webauth/cbor/cbor_writer_unittest.cc