Started here:
https://ci.chromium.org/buildbot/chromium.gpu.fyi/GPU%20FYI%20Win%20Clang%20Builder%20%28dbg%29/397

FAILED: pdfium_test.exe pdfium_test.exe.pdb 
E:/b/depot_tools/win_tools-2_7_6_bin/python/bin/python.exe ../../build/toolchain/win/tool_wrapper.py link-wrapper environment.x64 False link.exe /nologo /OUT:./pdfium_test.exe /PDB:./pdfium_test.exe.pdb @./pdfium_test.exe.rsp
obj/third_party/pdfium/fxcodec.lib : fatal error LNK1106: invalid file or disk full: cannot seek to 0x435CC4B1

A bit different error in next build:
https://ci.chromium.org/buildbot/chromium.gpu.fyi/GPU%20FYI%20Win%20Clang%20Builder%20%28dbg%29/398

FAILED: pdfium_embeddertests.exe pdfium_embeddertests.exe.pdb 
E:/b/depot_tools/win_tools-2_7_6_bin/python/bin/python.exe ../../build/toolchain/win/tool_wrapper.py link-wrapper environment.x64 False link.exe /nologo /OUT:./pdfium_embeddertests.exe /PDB:./pdfium_embeddertests.exe.pdb @./pdfium_embeddertests.exe.rsp
obj/third_party/pdfium/fxcodec.lib : fatal error LNK1106: invalid file or disk full: cannot seek to 0x435CC4B1
[8644/12640] LINK pdfium_unittests.exe pdfium_unittests.exe.pdb
FAILED: pdfium_unittests.exe pdfium_unittests.exe.pdb 
E:/b/depot_tools/win_tools-2_7_6_bin/python/bin/python.exe ../../build/toolchain/win/tool_wrapper.py link-wrapper environment.x64 False link.exe /nologo /OUT:./pdfium_unittests.exe /PDB:./pdfium_unittests.exe.pdb @./pdfium_unittests.exe.rsp
obj/third_party/pdfium/fxcodec.lib : fatal error LNK1106: invalid file or disk full: cannot seek to 0x435CC4B1

I don't see anything pdfium related in blamelist, so I assume this is an Infra issue.