From https://build.chromium.org/p/chromium.fyi/builders/ClangToTLinuxUBSanVptr/builds/5366:


[18476/42360] CXX obj/content/browser/browser/zygote_main_linux.o
FAILED: obj/content/browser/browser/zygote_main_linux.o 
../../third_party/llvm-build/Release+Asserts/bin/clang++ -MMD -MF obj/content/browser/browser/zygote_main_linux.o.d -DENABLE_SCREEN_CAPTURE=1 -DV8_DEPRECATION_WARNINGS -DUSE_UDEV -DUSE_AURA=1 -DUSE_PANGO=1 -DUSE_CAIRO=1 -DUSE_GLIB=1 -DUSE_NSS_CERTS=1 -DUSE_X11=1 -DUNDEFINED_SANITIZER -DFULL_SAFE_BROWSING -DSAFE_BROWSING_CSD -DSAFE_BROWSING_DB_LOCAL -DCHROMIUM_BUILD -DFIELDTRIAL_TESTING_ENABLED -DCR_CLANG_REVISION=\"304733\" -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -DSANITIZER_COVERAGE -DNDEBUG -DNVALGRIND -DDYNAMIC_ANNOTATIONS_ENABLED=0 -DCONTENT_IMPLEMENTATION -DV8_USE_EXTERNAL_STARTUP_DATA -DATK_LIB_DIR=\"/usr/lib/x86_64-linux-gnu\" -DUSE_GCONF -DGLIB_VERSION_MAX_ALLOWED=GLIB_VERSION_2_32 -DGLIB_VERSION_MIN_REQUIRED=GLIB_VERSION_2_26 -DGL_GLEXT_PROTOTYPES -DUSE_GLX -DUSE_EGL -DU_USING_ICU_NAMESPACE=0 -DU_ENABLE_DYLOAD=0 -DU_STATIC_IMPLEMENTATION -DICU_UTIL_DATA_IMPL=ICU_UTIL_DATA_FILE -DUCHAR_TYPE=uint16_t -DSK_IGNORE_LINEONLY_AA_CONVEX_PATH_OPTS -DSK_HAS_PNG_LIBRARY -DSK_HAS_WEBP_LIBRARY -DSK_HAS_JPEG_LIBRARY -DSK_SUPPORT_GPU=1 -DLEVELDB_PLATFORM_CHROMIUM=1 -DGOOGLE_PROTOBUF_NO_RTTI -DGOOGLE_PROTOBUF_NO_STATIC_INITIALIZER -DHAVE_PTHREAD -DFEATURE_ENABLE_VOICEMAIL -DEXPAT_RELATIVE_PATH -DGTEST_RELATIVE_PATH -DNO_SOUND_SYSTEM -DWEBRTC_CHROMIUM_BUILD -DWEBRTC_POSIX -DWEBRTC_LINUX -DNO_MAIN_THREAD_WRAPPING -DFLAC__NO_DLL -I../.. -Igen -I../../build/linux/debian_jessie_amd64-sysroot/usr/include/atk-1.0 -I../../build/linux/debian_jessie_amd64-sysroot/usr/include/glib-2.0 -I../../build/linux/debian_jessie_amd64-sysroot/usr/lib/x86_64-linux-gnu/glib-2.0/include -I../../build/linux/debian_jessie_amd64-sysroot/usr/include/gconf/2 -I../../build/linux/debian_jessie_amd64-sysroot/usr/include/dbus-1.0 -I../../build/linux/debian_jessie_amd64-sysroot/usr/lib/x86_64-linux-gnu/dbus-1.0/include -I../../build/linux/debian_jessie_amd64-sysroot/usr/include/glib-2.0 -I../../build/linux/debian_jessie_amd64-sysroot/usr/lib/x86_64-linux-gnu/glib-2.0/include -I../../build/linux/debian_jessie_amd64-sysroot/usr/include/glib-2.0 -I../../build/linux/debian_jessie_amd64-sysroot/usr/lib/x86_64-linux-gnu/glib-2.0/include -I../../build/linux/debian_jessie_amd64-sysroot/usr/include/pango-1.0 -I../../build/linux/debian_jessie_amd64-sysroot/usr/include/cairo -I../../build/linux/debian_jessie_amd64-sysroot/usr/include/glib-2.0 -I../../build/linux/debian_jessie_amd64-sysroot/usr/lib/x86_64-linux-gnu/glib-2.0/include -I../../build/linux/debian_jessie_amd64-sysroot/usr/include/pixman-1 -I../../build/linux/debian_jessie_amd64-sysroot/usr/include/libpng12 -I../../third_party/libwebp -I../../third_party/khronos -I../../gpu -I../../third_party/ced/src -I../../third_party/icu/source/common -I../../third_party/icu/source/i18n -I../../skia/config -I../../skia/ext -I../../third_party/skia/include/c -I../../third_party/skia/include/config -I../../third_party/skia/include/core -I../../third_party/skia/include/effects -I../../third_party/skia/include/encode -I../../third_party/skia/include/images -I../../third_party/skia/include/lazy -I../../third_party/skia/include/pathops -I../../third_party/skia/include/pdf -I../../third_party/skia/include/pipe -I../../third_party/skia/include/ports -I../../third_party/skia/include/utils -I../../third_party/skia/third_party/vulkan -I../../third_party/skia/include/gpu -I../../third_party/skia/src/gpu -I../../third_party/skia/src/sksl -I../../third_party/leveldatabase -I../../third_party/leveldatabase/src -I../../third_party/leveldatabase/src/include -I../../third_party/protobuf/src -Igen/protoc_out -Igen/components/metrics/proto -I../../third_party/protobuf/src -I../../third_party/libwebm/source -I../../third_party/boringssl/src/include -I../../build/linux/debian_jessie_amd64-sysroot/usr/include/nss -I../../build/linux/debian_jessie_amd64-sysroot/usr/include/nspr -Igen -I../../third_party/WebKit -Igen/third_party/WebKit -I../../v8/include -Igen/v8/include -I../../third_party/mesa/src/include -I../../third_party/angle/src/common/third_party/numerics -Igen/angle -I../../third_party/brotli/include -I../../third_party/libyuv/include -I../../third_party/re2/src -I../../third_party/zlib -I../../third_party/webrtc_overrides -I../../testing/gtest/include -I../../third_party -I../../third_party/webrtc_overrides -I../../third_party -I../../build/linux/debian_jessie_amd64-sysroot/usr/include/dbus-1.0 -I../../build/linux/debian_jessie_amd64-sysroot/usr/lib/x86_64-linux-gnu/dbus-1.0/include -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 -m64 -march=x86-64 -Wall -Werror -Wextra -Wno-missing-field-initializers -Wno-unused-parameter -Wno-c++11-narrowing -Wno-covered-switch-default -Wno-unneeded-internal-declaration -Wno-inconsistent-missing-override -Wno-undefined-var-template -Wno-nonportable-include-path -Wno-address-of-packed-member -Wno-unused-lambda-capture -Wno-user-defined-warnings -O2 -fno-ident -fdata-sections -ffunction-sections -fno-omit-frame-pointer -g1 --sysroot=../../build/linux/debian_jessie_amd64-sysroot -gline-tables-only -gcolumn-info -fno-omit-frame-pointer -fsanitize-coverage=trace-pc-guard -mllvm -sanitizer-coverage-prune-blocks=1 -fno-sanitize-recover=undefined -fsanitize=vptr -fsanitize-blacklist=../../tools/ubsan/vptr_blacklist.txt -fvisibility=hidden -Wheader-hygiene -Wstring-conversion -Wtautological-overlap-compare -Wexit-time-destructors -Wno-unused-local-typedef -Wno-unused-function -Wno-header-guard -std=gnu++11 -fno-exceptions -fvisibility-inlines-hidden -c ../../content/zygote/zygote_main_linux.cc -o obj/content/browser/browser/zygote_main_linux.o
../../content/zygote/zygote_main_linux.cc:586:7: error: use of undeclared identifier '__sanitizer_maybe_open_cov_file'
      __sanitizer_maybe_open_cov_file(sancov_file_name.c_str()));
      ^
1 error generated.