Don't know why I've only seen it on these two builders so far.  The error:

../../headless/lib/utility/headless_content_utility_client.cc(24,36):  error: 'headless::HeadlessContentUtilityClient::SetNetworkBinderCreationCallbackForTests' redeclared without 'dllimport' attribute: 'dllexport' attribute added [-Werror,-Winconsistent-dllimport]
  void HeadlessContentUtilityClient::SetNetworkBinderCreationCallbackForTests(
                                     ^
  ../..\headless/lib/utility/headless_content_utility_client.h(22,15):  note: previous declaration is here
    static void SetNetworkBinderCreationCallbackForTests(
                ^

suspect CL:
https://chromium-review.googlesource.com/c/chromium/src/+/1263566


first failures:
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/GPU%20FYI%20Win%20x64%20Builder%20%28dbg%29/5748
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/GPU%20FYI%20Win%20Clang%20Builder%20%28dbg%29/5576