Steps to reproduce the problem:
1. Check out to branch 67.0.3396.69, finish gclient sync
2. gn gen out/Debug-iphoneos --args='is_cronet_build=true enable_reporting=false use_xcode_clang=true ios_deployment_target="9.0" target_cpu="arm" target_os="ios" enable_websockets=false disable_file_support=true disable_ftp_support=true disable_brotli_filter=true use_platform_icu_alternatives=true is_component_build=false ios_enable_code_signing=false is_debug=false use_partition_alloc=false include_transport_security_state_preload_list=false use_sanitizer_coverage=true sanitizer_coverage_flags="func,trace-pc" enable_dsyms=true enable_stripping=true symbol_level=0' --ide=xcode
3. ninja -C out/Debug-iphoneos libcronet

What is the expected behavior?
Build should succeed

What went wrong?
Build failed with the following error messages:
[21/1873] CC obj/base/third_party/dynamic_annotations/dynamic_annotations/dynamic_annotations.o
FAILED: obj/base/third_party/dynamic_annotations/dynamic_annotations/dynamic_annotations.o
clang -MMD -MF obj/base/third_party/dynamic_annotations/dynamic_annotations/dynamic_annotations.o.d -DV8_DEPRECATION_WARNINGS -DNO_TCMALLOC -DCHROMIUM_BUILD -DFIELDTRIAL_TESTING_ENABLED -DCR_XCODE_VERSION=0931 -DCR_CLANG_REVISION=\"328716-2\" -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -DSANITIZER_COVERAGE -DNDEBUG -DNVALGRIND -DDYNAMIC_ANNOTATIONS_ENABLED=0 -DNS_BLOCK_ASSERTIONS=1 -I../.. -Igen -fno-strict-aliasing -fmerge-all-constants --param=ssp-buffer-size=4 -fstack-protector -Wno-builtin-macro-redefined -D__DATE__= -D__TIME__= -D__TIMESTAMP__= -fcolor-diagnostics -no-canonical-prefixes -arch armv7 -Wall -Werror -Wextra -Wimplicit-fallthrough -Wthread-safety -Wunguarded-availability -Wundeclared-selector -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-address-of-packed-member -Oz -fno-omit-frame-pointer -g0 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS11.3.sdk -stdlib=libc++ -miphoneos-version-min=9.0 -gline-tables-only -gcolumn-info -fsanitize-coverage=func,trace-pc -mllvm -sanitizer-coverage-prune-blocks=1 -mllvm -sanitizer-coverage-block-threshold=0 -fvisibility=hidden -Wheader-hygiene -Wstring-conversion -Wtautological-overlap-compare -std=c11 -c ../../base/third_party/dynamic_annotations/dynamic_annotations.c -o obj/base/third_party/dynamic_annotations/dynamic_annotations/dynamic_annotations.o
clang (LLVM option parsing): Unknown command line argument '-sanitizer-coverage-block-threshold=0'.  Try: 'clang (LLVM option parsing) -help'
clang (LLVM option parsing): Did you mean '-sanitizer-coverage-level=0'?
[22/1873] CC obj/base/third_party/libevent/libevent/event_tagging.o
FAILED: obj/base/third_party/libevent/libevent/event_tagging.o
clang -MMD -MF obj/base/third_party/libevent/libevent/event_tagging.o.d -DHAVE_CONFIG_H -DV8_DEPRECATION_WARNINGS -DNO_TCMALLOC -DCHROMIUM_BUILD -DFIELDTRIAL_TESTING_ENABLED -DCR_XCODE_VERSION=0931 -DCR_CLANG_REVISION=\"328716-2\" -DSANITIZER_COVERAGE -DNDEBUG -DNVALGRIND -DDYNAMIC_ANNOTATIONS_ENABLED=0 -DNS_BLOCK_ASSERTIONS=1 -I../../base/third_party/libevent/mac -I../.. -Igen -fno-strict-aliasing -fmerge-all-constants --param=ssp-buffer-size=4 -fstack-protector -Wno-builtin-macro-redefined -D__DATE__= -D__TIME__= -D__TIMESTAMP__= -fcolor-diagnostics -no-canonical-prefixes -arch armv7 -Oz -fno-omit-frame-pointer -g0 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS11.3.sdk -stdlib=libc++ -miphoneos-version-min=9.0 -gline-tables-only -gcolumn-info -fsanitize-coverage=func,trace-pc -mllvm -sanitizer-coverage-prune-blocks=1 -mllvm -sanitizer-coverage-block-threshold=0 -fvisibility=hidden -Wheader-hygiene -Wstring-conversion -Wtautological-overlap-compare -Werror -Wall -Wno-unused-variable -Wunguarded-availability -Wundeclared-selector -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-address-of-packed-member -std=c11 -c ../../base/third_party/libevent/event_tagging.c -o obj/base/third_party/libevent/libevent/event_tagging.o
clang (LLVM option parsing): Unknown command line argument '-sanitizer-coverage-block-threshold=0'.  Try: 'clang (LLVM option parsing) -help'
clang (LLVM option parsing): Did you mean '-sanitizer-coverage-level=0'?
[23/1873] CC obj/base/third_party/libevent/libevent/evbuffer.o
FAILED: obj/base/third_party/libevent/libevent/evbuffer.o
clang -MMD -MF obj/base/third_party/libevent/libevent/evbuffer.o.d -DHAVE_CONFIG_H -DV8_DEPRECATION_WARNINGS -DNO_TCMALLOC -DCHROMIUM_BUILD -DFIELDTRIAL_TESTING_ENABLED -DCR_XCODE_VERSION=0931 -DCR_CLANG_REVISION=\"328716-2\" -DSANITIZER_COVERAGE -DNDEBUG -DNVALGRIND -DDYNAMIC_ANNOTATIONS_ENABLED=0 -DNS_BLOCK_ASSERTIONS=1 -I../../base/third_party/libevent/mac -I../.. -Igen -fno-strict-aliasing -fmerge-all-constants --param=ssp-buffer-size=4 -fstack-protector -Wno-builtin-macro-redefined -D__DATE__= -D__TIME__= -D__TIMESTAMP__= -fcolor-diagnostics -no-canonical-prefixes -arch armv7 -Oz -fno-omit-frame-pointer -g0 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS11.3.sdk -stdlib=libc++ -miphoneos-version-min=9.0 -gline-tables-only -gcolumn-info -fsanitize-coverage=func,trace-pc -mllvm -sanitizer-coverage-prune-blocks=1 -mllvm -sanitizer-coverage-block-threshold=0 -fvisibility=hidden -Wheader-hygiene -Wstring-conversion -Wtautological-overlap-compare -Werror -Wall -Wno-unused-variable -Wunguarded-availability -Wundeclared-selector -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-address-of-packed-member -std=c11 -c ../../base/third_party/libevent/evbuffer.c -o obj/base/third_party/libevent/libevent/evbuffer.o
clang (LLVM option parsing): Unknown command line argument '-sanitizer-coverage-block-threshold=0'.  Try: 'clang (LLVM option parsing) -help'
clang (LLVM option parsing): Did you mean '-sanitizer-coverage-level=0'?
[24/1873] CC obj/base/third_party/libevent/libevent/event.o
FAILED: obj/base/third_party/libevent/libevent/event.o
clang -MMD -MF obj/base/third_party/libevent/libevent/event.o.d -DHAVE_CONFIG_H -DV8_DEPRECATION_WARNINGS -DNO_TCMALLOC -DCHROMIUM_BUILD -DFIELDTRIAL_TESTING_ENABLED -DCR_XCODE_VERSION=0931 -DCR_CLANG_REVISION=\"328716-2\" -DSANITIZER_COVERAGE -DNDEBUG -DNVALGRIND -DDYNAMIC_ANNOTATIONS_ENABLED=0 -DNS_BLOCK_ASSERTIONS=1 -I../../base/third_party/libevent/mac -I../.. -Igen -fno-strict-aliasing -fmerge-all-constants --param=ssp-buffer-size=4 -fstack-protector -Wno-builtin-macro-redefined -D__DATE__= -D__TIME__= -D__TIMESTAMP__= -fcolor-diagnostics -no-canonical-prefixes -arch armv7 -Oz -fno-omit-frame-pointer -g0 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS11.3.sdk -stdlib=libc++ -miphoneos-version-min=9.0 -gline-tables-only -gcolumn-info -fsanitize-coverage=func,trace-pc -mllvm -sanitizer-coverage-prune-blocks=1 -mllvm -sanitizer-coverage-block-threshold=0 -fvisibility=hidden -Wheader-hygiene -Wstring-conversion -Wtautological-overlap-compare -Werror -Wall -Wno-unused-variable -Wunguarded-availability -Wundeclared-selector -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-address-of-packed-member -std=c11 -c ../../base/third_party/libevent/event.c -o obj/base/third_party/libevent/libevent/event.o
clang (LLVM option parsing): Unknown command line argument '-sanitizer-coverage-block-threshold=0'.  Try: 'clang (LLVM option parsing) -help'
clang (LLVM option parsing): Did you mean '-sanitizer-coverage-level=0'?
[25/1873] CC obj/base/third_party/libevent/libevent/evrpc.o
FAILED: obj/base/third_party/libevent/libevent/evrpc.o
clang -MMD -MF obj/base/third_party/libevent/libevent/evrpc.o.d -DHAVE_CONFIG_H -DV8_DEPRECATION_WARNINGS -DNO_TCMALLOC -DCHROMIUM_BUILD -DFIELDTRIAL_TESTING_ENABLED -DCR_XCODE_VERSION=0931 -DCR_CLANG_REVISION=\"328716-2\" -DSANITIZER_COVERAGE -DNDEBUG -DNVALGRIND -DDYNAMIC_ANNOTATIONS_ENABLED=0 -DNS_BLOCK_ASSERTIONS=1 -I../../base/third_party/libevent/mac -I../.. -Igen -fno-strict-aliasing -fmerge-all-constants --param=ssp-buffer-size=4 -fstack-protector -Wno-builtin-macro-redefined -D__DATE__= -D__TIME__= -D__TIMESTAMP__= -fcolor-diagnostics -no-canonical-prefixes -arch armv7 -Oz -fno-omit-frame-pointer -g0 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS11.3.sdk -stdlib=libc++ -miphoneos-version-min=9.0 -gline-tables-only -gcolumn-info -fsanitize-coverage=func,trace-pc -mllvm -sanitizer-coverage-prune-blocks=1 -mllvm -sanitizer-coverage-block-threshold=0 -fvisibility=hidden -Wheader-hygiene -Wstring-conversion -Wtautological-overlap-compare -Werror -Wall -Wno-unused-variable -Wunguarded-availability -Wundeclared-selector -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-address-of-packed-member -std=c11 -c ../../base/third_party/libevent/evrpc.c -o obj/base/third_party/libevent/libevent/evrpc.o
clang (LLVM option parsing): Unknown command line argument '-sanitizer-coverage-block-threshold=0'.  Try: 'clang (LLVM option parsing) -help'
clang (LLVM option parsing): Did you mean '-sanitizer-coverage-level=0'?
[26/1873] CC obj/base/third_party/libevent/libevent/buffer.o
FAILED: obj/base/third_party/libevent/libevent/buffer.o
clang -MMD -MF obj/base/third_party/libevent/libevent/buffer.o.d -DHAVE_CONFIG_H -DV8_DEPRECATION_WARNINGS -DNO_TCMALLOC -DCHROMIUM_BUILD -DFIELDTRIAL_TESTING_ENABLED -DCR_XCODE_VERSION=0931 -DCR_CLANG_REVISION=\"328716-2\" -DSANITIZER_COVERAGE -DNDEBUG -DNVALGRIND -DDYNAMIC_ANNOTATIONS_ENABLED=0 -DNS_BLOCK_ASSERTIONS=1 -I../../base/third_party/libevent/mac -I../.. -Igen -fno-strict-aliasing -fmerge-all-constants --param=ssp-buffer-size=4 -fstack-protector -Wno-builtin-macro-redefined -D__DATE__= -D__TIME__= -D__TIMESTAMP__= -fcolor-diagnostics -no-canonical-prefixes -arch armv7 -Oz -fno-omit-frame-pointer -g0 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS11.3.sdk -stdlib=libc++ -miphoneos-version-min=9.0 -gline-tables-only -gcolumn-info -fsanitize-coverage=func,trace-pc -mllvm -sanitizer-coverage-prune-blocks=1 -mllvm -sanitizer-coverage-block-threshold=0 -fvisibility=hidden -Wheader-hygiene -Wstring-conversion -Wtautological-overlap-compare -Werror -Wall -Wno-unused-variable -Wunguarded-availability -Wundeclared-selector -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-address-of-packed-member -std=c11 -c ../../base/third_party/libevent/buffer.c -o obj/base/third_party/libevent/libevent/buffer.o
clang (LLVM option parsing): Unknown command line argument '-sanitizer-coverage-block-threshold=0'.  Try: 'clang (LLVM option parsing) -help'
clang (LLVM option parsing): Did you mean '-sanitizer-coverage-level=0'?
[27/1873] CC obj/base/third_party/libevent/libevent/evdns.o
FAILED: obj/base/third_party/libevent/libevent/evdns.o
clang -MMD -MF obj/base/third_party/libevent/libevent/evdns.o.d -DHAVE_CONFIG_H -DV8_DEPRECATION_WARNINGS -DNO_TCMALLOC -DCHROMIUM_BUILD -DFIELDTRIAL_TESTING_ENABLED -DCR_XCODE_VERSION=0931 -DCR_CLANG_REVISION=\"328716-2\" -DSANITIZER_COVERAGE -DNDEBUG -DNVALGRIND -DDYNAMIC_ANNOTATIONS_ENABLED=0 -DNS_BLOCK_ASSERTIONS=1 -I../../base/third_party/libevent/mac -I../.. -Igen -fno-strict-aliasing -fmerge-all-constants --param=ssp-buffer-size=4 -fstack-protector -Wno-builtin-macro-redefined -D__DATE__= -D__TIME__= -D__TIMESTAMP__= -fcolor-diagnostics -no-canonical-prefixes -arch armv7 -Oz -fno-omit-frame-pointer -g0 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS11.3.sdk -stdlib=libc++ -miphoneos-version-min=9.0 -gline-tables-only -gcolumn-info -fsanitize-coverage=func,trace-pc -mllvm -sanitizer-coverage-prune-blocks=1 -mllvm -sanitizer-coverage-block-threshold=0 -fvisibility=hidden -Wheader-hygiene -Wstring-conversion -Wtautological-overlap-compare -Werror -Wall -Wno-unused-variable -Wunguarded-availability -Wundeclared-selector -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-address-of-packed-member -std=c11 -c ../../base/third_party/libevent/evdns.c -o obj/base/third_party/libevent/libevent/evdns.o
clang (LLVM option parsing): Unknown command line argument '-sanitizer-coverage-block-threshold=0'.  Try: 'clang (LLVM option parsing) -help'
clang (LLVM option parsing): Did you mean '-sanitizer-coverage-level=0'?
[30/1873] CXX obj/build/config/sanitizers/options_sources/sanitizer_options.o

Did this work before? Yes 

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