refactor: do not pass a DesktopMediaList* to DesktopCapturer::OnListReady()
The list pointer was being used as a proxy for its type, so just pass
the type instead. This solves a lifecycle issue occurring in CI where
the callack can outlive the DesktopMediaList.
Sample error log:
[48471:0428/193441.269750:FATAL:base/allocator/partition_alloc_support.cc:798] Detected dangling raw_ptr in unretained with id=0x0000013c02e14378:
Task trace:
0 Electron Framework 0x000000012283a0ba electron::api::DesktopCapturer::ListObserver::MaybeNotifyReady() + 170
1 Electron Framework 0x0000000133246dc5 NativeDesktopMediaList::Worker::OnRecurrentCaptureResult(webrtc::DesktopCapturer::Result, std::__Cr::unique_ptr<webrtc::DesktopFrame, std::__Cr::default_delete<webrtc::DesktopFrame>>, long) + 357
2 Electron Framework 0x000000013328dbcf (anonymous namespace)::ScreenshotManagerCapturer::OnRecurrentCaptureTimer() + 1343
Stack trace:
0 Electron Framework 0x000000012ade42f2 base::debug::CollectStackTrace(base::span<void const*, 18446744073709551615ul, void const**>) + 18
1 Electron Framework 0x000000012add00e1 base::debug::StackTrace::StackTrace(unsigned long) + 225
2 Electron Framework 0x000000012ade978a base::allocator::UnretainedDanglingRawPtrDetectedCrash(unsigned long) + 90
3 Electron Framework 0x000000012ae437f7 base::internal::RawPtrBackupRefImpl<true>::ReportIfDanglingInternal(unsigned long) + 391
f8d041246c