feat: add webPreferences.enablePreferredSizeMode

[samuelmaddock]

Description of Change

For Chrome extension popups and options windows, the size of their frame corresponds to the minimum size of their document's layout. To enable this, RenderViewHost::EnablePreferredSizeMode exists to notify the RenderView to send back updates with its size. This gives an interesting result where the document can dictate its frame's size.

In practice, it looks like this:

Example code:

const view = new BrowserView({
  webPreferences: {
    preferredSizeMode: true,
  },
})
view.webContents.on('preferred-size-changed', (event, size) => {
  view.setBounds({ x: 0, y: 0, width: size.width, height: size.height })
})

I could see this being useful for specialized modal popups as well.

cc @electron/wg-api -- Question for you: is it worth adding tests for just adding bindings to existing Chromium functionality?

relates to #19447

Checklist

• PR description included and stakeholders cc'd
• npm test passes
• tests are changed or added
• relevant documentation is changed or added
• PR title follows semantic commit guidelines
• PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.

Release Notes

Notes: Added webPreferences.preferredSizeMode to allow sizing views according to their document's minimum size.

[samuelmaddock]

The location for calling this is based on Chromium's implementation: https://source.chromium.org/chromium/chromium/src/+/master:components/guest_view/browser/guest_view_base.cc;l=573;drc=d1252b1460e53a48e235c3bd9555bf5926c49100

[sentialx]

Great job! Could this be backported to 9-x-y?

[samuelmaddock]

Great job! Could this be backported to 9-x-y?

At the will of @electron/wg-releases, probably. I'd like to target 11-x-y at the least.

[ckerr]

This is pretty nice.

[ckerr]

linux CI failure seems unrelated: E1013 02:31:23.397542 22963 gomacc.cc:409] GOMA: compiler proxy not working?

[jkleinsc]

The API WG approved this at our Oct 19 2020 meeting.

[release-clerk]

Release Notes Persisted

Added webPreferences.preferredSizeMode to allow sizing views according to their document's minimum size.

[samuelmaddock]

@codebytere oof, I just realized the notes were not updated to reflect the renamed API. It should be webPreferences.enablePreferredSizeMode. How would one go about correcting that in the persisted release notes?