PSA: Blink's Device Sclae Factor and Zoom logic consolidation

[oshima]

Hi all

TL;DR We're planning to consolidate the internal mechanism to handle device scale factor and zooming. If you care HiDPI, or own HiDPI bugs, please read on.

Historically, they started as a different feature, but now both behave almost identical. (devicePixelRatio changes with zooming, zooming triggers media query change etc)

On the other hand, there are many HiDPI bugs that are already solved/handled correctly in zooming.

Instead of fixing them separately, we're going to use Zooming logic to implement DSF behavior.

There will be little difference from user's point of view. They still have a separate zooming option.

You can find the discussion crbug.com/485650 and the design doc here.

This will be enabled on CrOS first (hopefully on 49 but may slip), and other platforms will follow (ms TBD).

For any questions, please feel free to comment on bugs, design doc, or contact me.

- oshima

[oshima]

Hello,

This has been turned on for ChromeOS device as of r373881 (about a 10 days ago).

Please file a bug or let us know if you find any problem on chromeos hidpi devices.

(here are known issues: crbug.com/585043, crbug.com/584709).

For non chromeos, this will be off for m50.