The specification doesn't say ="" is required so there's no bug in Chrome.
https://www.w3.org/TR/html/syntax.html#elements-attributes

    Empty attribute syntax
    Just the attribute name. The value is implicitly the empty string.

Ok. Perhaps I need to move this to a feature request?

There are times when Chrome interprets title vs title="" differently. The <input type="file"> tag is a good example. If it has title, then Chrome creates its own tooltip for the element. If it has title="", then Chrome uses the empty string as the tooltip.

Following up, the spec says:

Empty attribute syntax --
Just the attribute name. The value is implicitly the empty string.

But in this case, Chrome is interpreting title differently than title="". This suggests the implicit value of title is not the same in both cases.

Since 'title' and 'title=""' are same as per HTML specification, it might make sense to submit a new bug report on Chrome's different handling of the tooltip, but that's for Chromium engineers to decide. BTW I don't see any difference in Windows - the standard tooltip is displayed in both cases as it should.

Thank you, that makes sense as a next step.

And I now see I presumed my problem was the missing ="", but on the Mac I'm getting same behavior as you on Windows. Here's what I see:

<input type="file"> ... produces a tooltip of "No file chosen"
<input type="file" title> ... produces a tooltip of "No file chosen"
<input type="file" title=""> ... produces a tooltip of "No file chosen"
<input type="file" title="something"> ... produces a tooltip of "something"

Given that title="something" produces a tooltip of "something" I would expect title="" to produce a tooltip of "", while an absent title attribute would lead Chrome to produce its own "No file chosen". 

I will file a new report re the tooltip handling--would this appropriately be a bug report or feature request? I'm guessing the latter.

As per comment #2 and #5, it seems to be a feature request. Hence, marking it as untriaged for further inputs from dev team.

Thanks...!!

I'm pretty sure this is not Blink specific. The decision to what to show on tooltip is UI/Browser. Reassigning.

The default tooltip appears to be controlled here in blink:
https://cs.chromium.org/chromium/src/third_party/blink/renderer/core/html/forms/file_input_type.cc?rcl=e6a59a6bf0c44a45fabe15389cd29373325eb4e8&l=413

kFileButtonNoFileSelectedLabel -> IDS_FORM_FILE_NO_FILE_LABEL -> "No file chosen"

The request sounds reasonable.
The code is in blink::ChromeClient::SetToolTip().

Can I take a look at this issue?

donghee.na92@, please go ahead.

@tkent

https://chromium-review.googlesource.com/c/chromium/src/+/1186930

CL is ready to review!

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6006113385396ec9d24faf9284756ea32cefd907

commit 6006113385396ec9d24faf9284756ea32cefd907
Author: Dong-hee Na <donghee.na92@gmail.com>
Date: Thu Aug 30 08:34:53 2018

HTML: Fix tooltips with an empty title attribute

Before this CL, the tooltip for an empty title attribute showed an
element-specific default tooltip message like "No file chosen" for
<input type=file>. But now it does not show any tooltip since the tooltip
message is considered as "".

The new behavior matches to Mozilla Firefox.

Bug:  872413 
Change-Id: I120a2bb7f9a6d244ceca660b79f9033e3a75af9e
Reviewed-on: https://chromium-review.googlesource.com/1186930
Reviewed-by: Kent Tamura <tkent@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/master@{#587483}
[modify] https://crrev.com/6006113385396ec9d24faf9284756ea32cefd907/content/test/test_blink_web_unit_test_support.cc
[modify] https://crrev.com/6006113385396ec9d24faf9284756ea32cefd907/third_party/blink/renderer/core/page/chrome_client.cc
[modify] https://crrev.com/6006113385396ec9d24faf9284756ea32cefd907/third_party/blink/renderer/core/page/chrome_client.h
[modify] https://crrev.com/6006113385396ec9d24faf9284756ea32cefd907/third_party/blink/renderer/core/page/chrome_client_test.cc