Thanks, Nico! Handing over to Yuke as he might be still working on setting the bots up.

The bots generating code coverage reports have also failed with:

[1/8498] STAMP obj/base/numerics/base_numerics.stamp
[2/8498] CXX obj/base/allocator/tcmalloc/atomicops-internals-x86.o
FAILED: obj/base/allocator/tcmalloc/atomicops-internals-x86.o 
../../third_party/llvm-build/Release+Asserts/bin/clang++ -MMD -MF obj/base/allocator/tcmalloc/atomicops-internals-x86.o.d -DNO_HEAP_CHECK -DV8_DEPRECATION_WARNINGS -DDCHECK_ALWAYS_ON=1 -DDCHECK_IS_CONFIGURABLE=1 -DUSE_UDEV -DUSE_AURA=1 -DUSE_GLIB=1 -DUSE_NSS_CERTS=1 -DUSE_X11=1 -DCLANG_COVERAGE -DFULL_SAFE_BROWSING -DSAFE_BROWSING_CSD -DSAFE_BROWSING_DB_LOCAL -DCHROMIUM_BUILD -DFIELDTRIAL_TESTING_ENABLED -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -DCR_CLANG_REVISION=\"332838-1\" -D_LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS -D_LIBCXXABI_DISABLE_VISIBILITY_ANNOTATIONS -DCR_LIBCXX_REVISION=332543 -DCR_LIBCXXABI_REVISION=331450 -DCR_SYSROOT_HASH=4e7db513b0faeea8fb410f70c9909e8736f5c0ab -DSANITIZER_COVERAGE -DNDEBUG -DNVALGRIND -DDYNAMIC_ANNOTATIONS_ENABLED=0 -DTCMALLOC_DONT_REPLACE_SYSTEM_ALLOC -I../../base/allocator -I../../third_party/tcmalloc/chromium/src/base -I../../third_party/tcmalloc/chromium/src -I../.. -Igen -fno-strict-aliasing --param=ssp-buffer-size=4 -fstack-protector -Wno-builtin-macro-redefined -D__DATE__= -D__TIME__= -D__TIMESTAMP__= -funwind-tables -fPIC -pipe -B../../third_party/binutils/Linux_x64/Release/bin -pthread -fcolor-diagnostics -fmerge-all-constants -Xclang -mllvm -Xclang -instcombine-lower-dbg-declare=0 -fdebug-prefix-map=/chromium/src/out/coverage=. -no-canonical-prefixes -m64 -march=x86-64 -fno-omit-frame-pointer -g1 -fprofile-instr-generate -fcoverage-mapping -mllvm -limited-coverage-experimental=true -fno-cxa-atexit -gline-tables-only -gcolumn-info -fsanitize-coverage=trace-pc-guard -mllvm -sanitizer-coverage-prune-blocks=1 -fvisibility=hidden -Xclang -load -Xclang ../../third_party/llvm-build/Release+Asserts/lib/libFindBadConstructs.so -Xclang -add-plugin -Xclang find-bad-constructs -Xclang -plugin-arg-find-bad-constructs -Xclang enforce-in-thirdparty-webkit -Xclang -plugin-arg-find-bad-constructs -Xclang check-enum-max-value -Xclang -plugin-arg-find-bad-constructs -Xclang check-ipc -Wheader-hygiene -Wstring-conversion -Wtautological-overlap-compare -Werror -Wall -Wno-unused-variable -Wno-missing-field-initializers -Wno-unused-parameter -Wno-c++11-narrowing -Wno-covered-switch-default -Wno-unneeded-internal-declaration -Wno-undefined-var-template -Wno-nonportable-include-path -Wno-address-of-packed-member -Wno-unused-lambda-capture -Wno-user-defined-warnings -Wno-enum-compare-switch -Wno-null-pointer-arithmetic -Wno-ignored-pragma-optimize -Wno-reorder -Wno-unused-function -Wno-unused-local-typedefs -Wno-unused-private-field -Wno-sign-compare -Wno-unused-result -O2 -fno-ident -fdata-sections -ffunction-sections -std=gnu++14 -fno-exceptions -fno-rtti -nostdinc++ -isystem../../buildtools/third_party/libc++/trunk/include -isystem../../buildtools/third_party/libc++abi/trunk/include --sysroot=../../build/linux/debian_sid_amd64-sysroot -fvisibility-inlines-hidden -c ../../third_party/tcmalloc/chromium/src/base/atomicops-internals-x86.cc -o obj/base/allocator/tcmalloc/atomicops-internals-x86.o
clang++: error: unknown argument: '-fno-cxa-atexit'

I'll upload a fix

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/85dcf76e792c7aac74ad739e47334d2c52c66c20

commit 85dcf76e792c7aac74ad739e47334d2c52c66c20
Author: Max Moroz <mmoroz@chromium.org>
Date: Fri Jun 01 19:06:04 2018

[Code Coverage] Fix clang flags: use "-fno-use-cxa-atexit" instead of "-fno-cxa-atexit".

TBR=mmoroz@chromium.org

Bug:  848803 
Change-Id: I3d951581422e67c826fe6ac9f5164aa4bc8b9dcf
Reviewed-on: https://chromium-review.googlesource.com/1081886
Reviewed-by: Yuke Liao <liaoyuke@chromium.org>
Reviewed-by: Reid Kleckner <rnk@chromium.org>
Reviewed-by: Max Moroz <mmoroz@chromium.org>
Commit-Queue: Max Moroz <mmoroz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#563747}
[modify] https://crrev.com/85dcf76e792c7aac74ad739e47334d2c52c66c20/build/config/coverage/BUILD.gn