fix: move NativeWindow tracking to OSR WCV

[adill]

Description of Change

In #15046, when we re-enabled OSR for 4.0.x, it seems passing in a NativeWindow to the constructor of OffScreenRenderWidgetHostView became optional with the intent that SetOwnerWindow would call into SetNativeWindow -- in my experience this just isn't happening.

When SetOwnerWindow is called initially (at https://github.com/electron/electron/blob/master/atom/browser/api/atom_api_browser_window.cc#L78) content::WebContents::GetRenderWidgetHostView returns nullptr (it hasn't been created yet) and it was never called again.

I haven't dug in too deep with regards to the root causes but missing out on initialization with a NativeWindow caused my OSR window to never paint (without debugger shenanigans.) This PR restores the behavior of constructing the OffScreenRenderWidgetHostView with a valid NativeWindow.

I have no idea if this is the "right" solution, so I'm certainly open for alternate solutions, but I figured I'd open the discussion with a PR that "works for me."

NB: I tried using the NativeWindowRelay like is used elsewhere in OffScreenWebContentsView but it, of course, has no entry until SetOwnerWindow is called.

Checklist

• PR description included and stakeholders cc'd
• npm test passes
• PR title follows semantic commit guidelines

Release Notes

Notes: fix: move NativeWindow tracking to OSR WCV

[brenca]

We could try to make this a bit less cast-y by moving the native window tracking to OffScreenWebContentsView, that is explicitly created when the api::WebContents is created, so that should already exist when SetOwnerWindow is called.

[adill]

@brenca Thanks! I updated the branch with your patch.

[brenca]

lgtm, but would like a second opinion, @codebytere maybe?

[groundwater]

Approve to get groups checked, but still waiting on @ckerr @codebytere

[codebytere]

@zcbenz this needs your approval for the two missing codeowner teams when you have a moment :)

[release-clerk]

Release Notes Persisted

fix: move NativeWindow tracking to OSR WCV

[codebytere]

/trop run backport-to 4-0-x

[trop]

The backport process for this PR has been manually initiated,
sending your 1's and 0's to "4-0-x" here we go! :D

[trop]

I was unable to backport this PR to "4-0-x" cleanly;
you will need to perform this backport manually.