Expected result:

http://www.gtalbot.org/BrowserBugsSection/CSS3Backgrounds/reference/ref-filled-green-100px-square.xht

2 additional tests with identical actual results (incorrect behaviors):

background-size: 10% auto;
http://www.gtalbot.org/BrowserBugsSection/CSS3Backgrounds/draft-background-size-percent-auto-no-intrinsic-0xx.xht


background-size: 10px auto;
http://www.gtalbot.org/BrowserBugsSection/CSS3Backgrounds/draft-background-size-length-auto-no-intrinsic-0xx.xht


The failure (bug) is really about when image has no intrinsic ratio or has no intrinsic size, then 100% should be used.

"
An 'auto' value for one dimension is resolved by using the image's intrinsic ratio and the size of the other dimension, or failing that, using the image's intrinsic size, or failing that, *_treating it as 100%_*.
"
CSS Backgrounds and Borders Module Level 3
3.9. Sizing Images: the 'background-size' property
https://drafts.csswg.org/css-backgrounds/#the-background-size

2 additional tests with identical actual results (incorrect behaviors) *_using SVG image_* with no intrinsic ratio:

background-size: 10% auto;
http://www.gtalbot.org/BrowserBugsSection/CSS3Backgrounds/draft-background-size-percent-auto-no-intrinsic-0xy.xht

background-size: 10px auto;
http://www.gtalbot.org/BrowserBugsSection/CSS3Backgrounds/draft-background-size-length-auto-no-intrinsic-0xy.xht

Able to reproduce this issue on Windows 10,Ubuntu 14.04 and Mac 10.12.4 with chrome stable #57.0.2987.133, Canary # 60.0.3074.0 and also in earlier version #30.0.1549.0

This is a non-regression issue, hence marking it as untriaged.

Attaching a screen-cast for reference. 

Deleted: Issue 711489.mp4 243 KB

	Issue 711489.mp4 243 KB View Download

Equivalent WebKit bug:
https://bugs.webkit.org/show_bug.cgi?id=170834

- - - - - 

In all fairness, the summary (title) of this Issue would be better, more consequent if worded like this:

background-position with 'auto' value when image has no intrinsic size incorrect

Duh! 

The summary (title) of this Issue should say *_background-size_* and not background-position! All 6 tests mention in this Issue are testing background-size and not background-position.

So:

the summary (title) of this Issue would be better, more consequent if worded like this:

background-size with 'auto' value when image has no intrinsic size incorrect

This works in Firefox, and fails in Safari (as in Chrome).

Gérard, perhaps you want to report the issue for Safari/WebKit as well? (If you haven't already.)

I hope it will get fixed in both Chrome and Safari.

Oh, you had already reported it for WebKit:

https://bugs.webkit.org/show_bug.cgi?id=170834

I hope it will get fixed in both Chrome and Safari ...

Tobi Reif,

I think the component for this issue should be Blink>Layout and not UI; the issue has not been triaged yet anyway.

I still want to submit the 6 tests mentioned here into the CSS3 Backgrounds and Borders test suite (under different and more suitable filenames)... along with many other tests that I also want to submit...

**UI mass Triage**

We were unable to reproduce this bug on Canary #72.0.3616.0. If this bug still reproduces for you, please reopen or file a new issue. Thanks!