Checked the issue on reported chrome version 63.0.3239.132 and on the latest canary 65.0.3310.0 using Windows 10 with the below mwntioned steps. 
1. Launched chrome 
2. Navigated to https://chromiumbugs.appspot.com/static/images/logo.png

We observed that black background isn't covering complete chrome rather we see boxy white corners on reported and latest versions as mentioned above.
We checked the same issue on M50(50.0.2661.0) there we observed an other behavior where chrome is seen completely on a white background with out any black traces. Attaching the screenshot of the same.

@Reporter: As per comment#0 we assume in good behavior the chrome should be surronded with black background with out boxy white corners. It would be highly helpful if given a confirmation on this by looking at the attached screen shot. 

Thanks! 

Deleted: 799168.PNG 287 KB

	799168.PNG 287 KB View Download

Correct. If the background is going to be black, then transparency should be black too.

Thank you for providing more feedback. Adding requester "vamshi.kommuri@techmahindra.com" to the cc list and removing "Needs-Feedback" label.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Thanks for the confirmation!

As per the confirmation given by the reporter from comment#2 considering black border having chrome with boxy white edges as an issue, able to reproduce it on reported version 63.0.3239.132 and on the latest 65.0.3313.0 using Windows 10, Mac 10.13.1 and Ubuntu 14.04. The UI is different in M50(50.0.2661.0), as the issue/UI is seen from the introduction of M57 hence considering it as non-regression and marking it as Untriaged.

Thanks!

We're probably explicitly deciding to put a white background so that transparent images blend with white. I agree it looks silly here

Should be easy enough to fix but does leave open the question of what exactly we would like to appear behind a transparent or partially transparent image in the image viewer like this.

UI, what do you think?

The background is a checkerboard pattern - it's just very faint/low contrast. (Maybe the gray should be darker...)

Independently confirmed what fs@ said. I'll see if it can be made better but we're not going to change the fundamental approach.

If we're going to put something other than a checkerboard pattern in the rest of the page (e.g. fill it with black as in the screenshots above), then I agree with comment 2 that the image should be "transparent to that background color".

This is problematic when using Chrome like a true image editor, but I think better reflects user expectations in the common case.

Personally, my opinion would be that since Chrome is simply a viewer and not an image editor, it should just display the transparency to the background color (similar to how Windows Photo Viewer displays transparency), because that's what transparency is. In my opinion, there isn't really a point in using transparency if it's going to be interpreted by a viewer as a checkerboard pattern. On the other hand, if it were an image editor (which is not the case here), I would say that a checkerboard pattern would be the most appropriate for representing transparency. But that's all just my 2 cents.

I also think we're a viewer so will change it to be the same as the body background (effectively no background to the image), which has the pleasant side effect of being much more efficient for us to paint.

I agree with changing it to the background color over the checkerboard pattern, since it is simply a viewer and not an image editor. Imagine transparency in favicons being displayed as a checkerboard pattern. If transparency is not displayed as "transparent" (where the color is the same as if it were not part of the image) but rather displayed as a checkerboard pattern even in viewers, then transparency is no longer true "transparency" as it was originally intended.

And thanks 93m4qau783@ for engaging and pointing out room for improvement. We appreciate it.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/eab1ec606de5921ae4e78ce5ce690076e0a37a71

commit eab1ec606de5921ae4e78ce5ce690076e0a37a71
Author: Stephen Chenney <schenney@chromium.org>
Date: Thu Jan 11 17:10:44 2018

[PE] Use body background for image urls

We had been displaying image urls with a very low contrast light colored
checkerboard, as you might see in image editing software. There was
agreement on the team to change it to use the page background color,
which better matches our function as a image display platform.

BUG= 799168 
R=pkasting@chromium.org,fs@opera.com

Change-Id: Ia676b05c80f91db9d7c5798e1938f1da6435db1b
Reviewed-on: https://chromium-review.googlesource.com/860498
Commit-Queue: Stephen Chenney <schenney@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#528650}
[modify] https://crrev.com/eab1ec606de5921ae4e78ce5ce690076e0a37a71/third_party/WebKit/LayoutTests/images/huge-image-viewport-scale-expected.txt
[modify] https://crrev.com/eab1ec606de5921ae4e78ce5ce690076e0a37a71/third_party/WebKit/Source/core/html/ImageDocument.cpp
[modify] https://crrev.com/eab1ec606de5921ae4e78ce5ce690076e0a37a71/third_party/WebKit/Source/core/html/ImageDocument.h

Verified on Chromium build 528863 / Chromium version 65.0.3319.0 from download-chromium.appspot.com.

Can you change the status to Verified?