First failing build:
https://build.chromium.org/p/chromium/builders/Win/builds/42187

Error:

[23924/32559] CXX obj\chrome\browser\extensions\browser_extensions.path_util.obj
FAILED: ninja -t msvc -e environment.x86 -- C:\b\build\goma/gomacc "C:\b\depot_tools\win_toolchain\vs_files\95ddda401ec5678f15eeed01d2bee08fcbc5ee97\VC\bin\amd64_x86\cl.exe" /nologo /showIncludes /FC @obj\remoting\test\chromoting_test_driver.chromoting_test_fixture.obj.rsp /c ..\..\remoting\test\chromoting_test_fixture.cc /Foobj\remoting\test\chromoting_test_driver.chromoting_test_fixture.obj /Fdobj\remoting\chromoting_test_driver.cc.pdb 
c:\b\build\slave\win\build\src\third_party\webrtc\modules\desktop_capture\desktop_geometry.h(14): fatal error C1083: Cannot open include file: 'webrtc/base/constructormagic.h': No such file or directory
ninja: build stopped: subcommand failed.


The only remotely related CL seems to be:
https://chromium.googlesource.com/chromium/src/+/7d8f6c45bc65d9a27b83ad9fd736b90798931c07

It looks like sergeyu@ already knows about this. Assigning to him.