I don't think I can help much with Mac unfortunately, I've never done any development for it. I don't know how much work needs to be done either, hopefully it is trivial but there's a lot of platform-specific UI code floating around.

Ok, thanks anyway.  ccameron: Any idea who might be a good owner for this? 

It would be great if we could get someone on the Mac team to help with this.

(Sorry, just getting back from OOO)

I just ran with the flag, and there are a few issues that need to be fixed, but nothing crashed. Offhand (see screenshots),
- the overlay scrollbars are wrong (not sure what's up there)
- the native controls are wrong (this makes some sense, because we don't use the native controls when we're zoomed ... but we should).

Adding vmiura@ (gpu/compositing manager) and shrike@ (mac manager). One of them may be able to get someone to help. I know that the mac team has chronic staffing problems, but we do have lots of compositing engineers who can work on Mac.

Deleted: Screen Shot 2017-05-04 at 3.11.36 PM.png 223 KB

	Screen Shot 2017-05-04 at 3.11.36 PM.png 223 KB View Download

Deleted: Screen Shot 2017-05-04 at 3.12.13 PM.png 562 KB

	Screen Shot 2017-05-04 at 3.12.13 PM.png 562 KB View Download

#5, Thank you for trying this on Mac. Last time I tested, (just compiled and enabled on mac), it had problem with fonts as well.

Did text rendering look ok?

The text looks reasonable to me, but I'm not a font-connoisseur, so I may be missing something.

I'm not sure what this change is exactly, or what to look for in terms of differences with the flag enabled. Also, ccameron@ says there are problems with overlay scrollbars and controls being wrong but I'm not sure what he's referring to (the screenshots don't make it clear, at least not to me).

What is the outline of what may need to be done here?  Passing the appropriate scale when rendering Changing Mac themes?

Attaching an annotated screenshot.

When we change page zoom on Mac, we no longer use the native theme (you'll see this on crbug if you do command-plus or command-minus). It would be nice to fix this problem in general.

The scrollbar thumb is a shrunk.

The native theme drawing code (and the native scrollbar drawing code) in Blink are among the hairiest in the land. MacViews is solving these same problems, so we may want to discuss merging the widget painting code at some point.

Deleted: dsf.png 789 KB

	dsf.png 789 KB View Download

In the best case scenario the only thing that needs to be done is changing IsUseZoomForDSFEnabledByDefault content_switches_internal.cc so that it's true on Mac. But since there's a lot of platform-specific UI code, some stuff may break. Once everything is fixed, then you're done.

When I did this for Windows, I saw problems in these areas:
* Scrollbars
* <input> widgets (like the date picker)
* The inspector
* Focus highlights
* Spelling error highlights
* PDFs
A lot of those are fully cross-platform, so I don't expect you to have to redo my fixes for Mac, but a smoke test would be good. My main point is that turning the flag on can cause problems in unexpected areas.

This issue has been Available for over a year. If it's no longer important or seems unlikely to be fixed, please consider closing it out. If it is important, please re-triage the issue.

Sorry for the inconvenience if the bug really should have been left as Available.

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

We should still do this at some point, even if just so we can clean up the multiple codepaths. With MacViews this should be a lot easier (more code is shared cross-platform).

cc ellyjones@ to put this on the Mac team's radar.

We (Mac and security teams) are interested in removing the usage of Cocoa from the renderers (issue 846357).