1655959 - Move nsIContentViewer::overrideDPPX to BrowsingContext

Status: NEW

(Core :: DOM: Navigation, enhancement, P3)

Description

[Alexandre Poirot [:ochameau]]

This attribute is used by DevTools and is expected to be also applied to remoted Fission iframe.
By setting this attribute on nsIContentViewer, we don't ensure applying it to remote iframe, which spawn another nsIContentViewer in their distinct process.
The typical way to fix that is to move such attribute up to BrowsingContext class.
You can take example on bug 1593708, which moved inRDMPanel from PresShell up to BrowsingContext. Or bug 1620966, which moved watchedByDevTools from DocShell up to BrowsingContext.

I imagine that it may also fix non-devtools usecase if this attribute is toggled outside of DevTools.
See bug 1591120 for extensive context.

Comment 1

[Emilio Cobos Álvarez (:emilio)]

Where is it used outside of devtools?

Comment 2

[Alexandre Poirot [:ochameau]]

Sorry, I mass opened these bugs. This one attribute is only used by DevTools and RemoteAgent
If the question was meant to triage this to DevTools, I'm totally fine with that.

Comment 3

[Emilio Cobos Álvarez (:emilio)]

No not really, sorry, was just curiosity :)

I'm curious about when is this useful, because this is a pretty odd one. It affects media queries and window.devicePixelRatio, but it doesn't affect rendering in any way.

Comment 4

[Mats Palmgren (inactive)]

I don't see why nsIContentViewer/nsIDocShell/BrowsingContext bugs should be filed in Core/Layout.
Please move them to a more appropriate component. (DOM/Navigation probably)

Comment 5

[Alexandre Poirot [:ochameau]]

Sure, I wasn't sure where to triage such work.

Comment 6

[Mats Palmgren (inactive)]

FYI, the moz.build files usually have a default Bugzilla component for the files in that sub-tree.
https://searchfox.org/mozilla-central/rev/cffd9b5302b6b6f51533d895a785b48ff418aec1/docshell/moz.build#8

Comment 7

[Chris Peterson [:cpeterson]]

Tracking dt-fission-m2-reserve bugs for Fission Beta milestone (M7).

Comment 8

[Neha Kochar [:neha]]

Bulk move of all dt-fission-m2-reserve bugs to Fission MVP milestone.

Comment 9

[Chris Peterson [:cpeterson]]

Moving old "dt-fission-m2-reserve" bugs to "dt-fission-future" because they don't block Fission MVP.