The failures started with this build: https://build.chromium.org/p/chromium.gpu/builders/Win7%20Debug%20%28NVIDIA%29/builds/56044, and each of them is failing with the same crash.

[1025/122136.313:FATAL:sandbox_win.cc(683)] Check failed: result == 0. 
Backtrace:
	base::debug::StackTrace::StackTrace [0x100C0826+102]
	base::debug::StackTrace::StackTrace [0x100BF3C3+35]
	logging::LogMessage::~LogMessage [0x10135505+149]
	service_manager::SandboxWin::InitBrokerServices [0x0D0D7EF9+1241]
	service_manager::Sandbox::Initialize [0x0D0D2649+73]
	content::InitializeSandbox [0x1BF14996+38]
	content::ContentMainRunnerImpl::Initialize [0x2069BF67+1767]
	content::ContentServiceManagerMainDelegate::Initialize [0x2069A479+57]
	service_manager::Main [0x0DD06530+784]
	content::ContentMain [0x2069B35A+74]
	ChromeMain [0x10AD72E5+501]
	MainDllLoader::Launch [0x0043065A+1178]
	wWinMain [0x00423623+1363]
	invoke_main [0x006B327E+30] (f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:123)
	__scrt_common_main_seh [0x006B30F0+336] (f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:283)
	__scrt_common_main [0x006B2F8D+13] (f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:326)
	wWinMainCRTStartup [0x006B32F8+8] (f:\dd\vctools\crt\vcstartup\src\startup\exe_wwinmain.cpp:17)
	BaseThreadInitThunk [0x7650338A+18]
	RtlInitializeExceptionChain [0x77B69902+99]
	RtlInitializeExceptionChain [0x77B698D5+54]

I'm suspecting its this change: https://chromium-review.googlesource.com/c/chromium/src/+/724227.