The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/53cf4f2c9884188d7625b2387fdc45c5aec61e5d

commit 53cf4f2c9884188d7625b2387fdc45c5aec61e5d
Author: tkent <tkent@chromium.org>
Date: Wed Jun 29 14:54:17 2016

UseCounter: Count usage of textarea[maxlength] and textarea[minlength].

This is a preparation for a possible specification change.
https://github.com/whatwg/html/issues/1467

BUG= 624361 
TBR=isherman@chromium.org

Review-Url: https://codereview.chromium.org/2104893005
Cr-Commit-Position: refs/heads/master@{#402806}

[modify] https://crrev.com/53cf4f2c9884188d7625b2387fdc45c5aec61e5d/third_party/WebKit/Source/core/frame/UseCounter.h
[modify] https://crrev.com/53cf4f2c9884188d7625b2387fdc45c5aec61e5d/third_party/WebKit/Source/core/html/HTMLTextAreaElement.cpp
[modify] https://crrev.com/53cf4f2c9884188d7625b2387fdc45c5aec61e5d/tools/metrics/histograms/histograms.xml

The specification has been updated so that a single line break is counted as 1.
https://github.com/whatwg/html/commit/163703186794c21daa92cc2718218afa44f26071

We should do
 1. Wait until the counters of #2 become stable.  That is to say, M53 stable push.
 2. Create chromestatu.com entry
 3. If the counters are not ignorable, send an intent-to-ship to blink-dev.
 4. Change the behavior.

Intent-to-ship was approved.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a15474ff7adff41a8956ab436ac63a7d5b7a090f

commit a15474ff7adff41a8956ab436ac63a7d5b7a090f
Author: tkent <tkent@chromium.org>
Date: Wed Sep 28 04:21:15 2016

Change the linebreak behavior of minlength and maxlength attributes of TEXTAREA.

Change it in response to a specification change, and to improve compatibility with
Firefox and Edge.

Old behavior:
 CRLF, CR, or LF is counted as 2 because we limited the submission value.

New behavior:
 CRLF, CR, or LF is counted as 1 because we limit the API value.

We can use HTMLTextAreaElement::value().length() as is because it's the API value,
and other string input should be counted by computeLengthForAPIValue().

Approved intent-to-ship:
https://groups.google.com/a/chromium.org/d/msg/blink-dev/MkSfvCan7kY/PgniO8jwAAAJ

BUG= 624361 

Review-Url: https://codereview.chromium.org/2380473002
Cr-Commit-Position: refs/heads/master@{#421445}

[modify] https://crrev.com/a15474ff7adff41a8956ab436ac63a7d5b7a090f/third_party/WebKit/LayoutTests/fast/forms/textarea/textarea-maxlength-expected.txt
[modify] https://crrev.com/a15474ff7adff41a8956ab436ac63a7d5b7a090f/third_party/WebKit/LayoutTests/fast/forms/textarea/textarea-maxlength.html
[modify] https://crrev.com/a15474ff7adff41a8956ab436ac63a7d5b7a090f/third_party/WebKit/LayoutTests/fast/forms/validationMessage-expected.txt
[modify] https://crrev.com/a15474ff7adff41a8956ab436ac63a7d5b7a090f/third_party/WebKit/Source/core/html/HTMLTextAreaElement.cpp
[modify] https://crrev.com/a15474ff7adff41a8956ab436ac63a7d5b7a090f/third_party/WebKit/Source/core/html/HTMLTextAreaElementTest.cpp

That's all which we can do.
WebKit and Edge violate the specification about non-BMP characters, but we can't do anything for them.