fix: set display_id in desktop capturer on Linux

[jamesnvc]

Description of Change

Previously, display_id was an empty string on Linux, pending Chrome support for
sharing individual screens. Now that this has been added, it is
desirable to have this property set correctly.

Addresses #27732.

Checklist

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

notes: Provided display_id for desktopCapturer on Linux.

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[jamesnvc]

I've "tested" ad-hoc, by running the built electron, but running npm test is giving me errors trying to install things (an apparently "ignorable" error from node-gyp installing abstract-socket, but then it fails building in src/electron-spec, being unable to build is-valid-window (fixed that error) in some python script, saying it can't find something in a path that isn't even inside the project.

[jamesnvc]

I also understand that this fix is for "Linux", but is currently X11-only. Is there a build flag or some-such I should be using instead of BUILDFLAG(IS_LINUX) to only do this on Linux+X11 platforms?

[jamesnvc]

(I'm also quite sure that the code here should be moved elsewhere -- I originally wrote the helper functions in ui/base/x/x11_display_util.cc, (which I guess is actually Chrome?) and just moved it in here so it would be self-contained & all in electron-land.)

[RaisinTen]

I also understand that this fix is for "Linux", but is currently X11-only. Is there a build flag or some-such I should be using instead of BUILDFLAG(IS_LINUX) to only do this on Linux+X11 platforms?

I believe what you're looking for is USE_OZONE_PLATFORM_X11. You should define it first like

electron/shell/browser/native_window_views.h

Lines 19 to 24 in 160d692

	#if defined(USE_OZONE)
	#include "ui/ozone/buildflags.h"
	#if BUILDFLAG(OZONE_PLATFORM_X11)
	#define USE_OZONE_PLATFORM_X11
	#endif
	#endif

and then use it like

electron/shell/browser/native_window_views.cc

Lines 541 to 544 in 160d692

	#if defined(USE_OZONE_PLATFORM_X11)
	if (IsX11())
	return !event_disabler_.get();
	#endif

wherever you need it.

[jamesnvc]

Thanks for the tip @RaisinTen! Updated the PR.

[zcbenz]

There is a lint warning

$ node ./script/lint.js && npm run lint:clang-format && npm run lint:docs
--- a/shell/browser/api/electron_api_desktop_capturer.cc
+++ b/shell/browser/api/electron_api_desktop_capturer.cc
@@ -39,7 +39,7 @@
 #include "ui/gfx/x/randr.h"
 #include "ui/gfx/x/x11_atom_cache.h"
 #include "ui/gfx/x/xproto_util.h"
-#endif // defined(USE_OZONE_PLATFORM_X11)
+#endif  // defined(USE_OZONE_PLATFORM_X11)
 #endif  // BUILDFLAG(IS_WIN)

[jamesnvc]

There is a lint warning

Oops, thank-you, fixed.

[ckerr]

Overall looks pretty sane. I had a few questions/comments but no fundamental change requests.

[jkleinsc]

@jamesnvc can you rebase this PR with the latest from main?

[jamesnvc]

@jamesnvc can you rebase this PR with the latest from main?

Done

[jkleinsc]

GN failures need to be addressed

[trop]

I have automatically backported this PR to "20-x-y", please check out #35834

[trop]

I have automatically backported this PR to "19-x-y", please check out #35835

[ckerr]

/trop run backport-to 21-x-y

[trop]

The backport process for this PR has been manually initiated - sending your PR to 21-x-y!

[trop]

I have automatically backported this PR to "21-x-y", please check out #35836