https://logs.chromium.org/v/?s=chromium%2Fbuildbucket%2Fcr-buildbucket.appspot.com%2F8942251885137264368%2F%2B%2Fsteps%2Fcompile%2F0%2Fstdout
FAILED: obj/third_party/blink/renderer/core/unit_tests/animation_sim_test.o 
export DEVELOPER_DIR=/b/s/w/ir/cache/builder/src/build/mac_files/Xcode.app;  /b/s/w/ir/cache/goma/client/gomacc ../../third_party/llvm-build/Release+Asserts/bin/clang++ -MMD -MF obj/third_party/blink/renderer/core/unit_tests/animation_sim_test.o.d -DV8_DEPRECATION_WARNINGS -DNO_TCMALLOC -DFULL_SAFE_BROWSING -DSAFE_BROWSING_CSD -DSAFE_BROWSING_DB_LOCAL -DCHROMIUM_BUILD -DFIELDTRIAL_TESTING_ENABLED -D_LIBCPP_HAS_NO_ALIGNED_ALLOCATION -DCR_XCODE_VERSION=0832 -DCR_CLANG_REVISION=\"335864-1\" -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D_FORTIFY_SOURCE=2 -D__ASSERT_MACROS_DEFINE_VERSIONS_WITHOUT_UNDERSCORE=0 -DNDEBUG -DNVALGRIND -DDYNAMIC_ANNOTATIONS_ENABLED=0 -DBLINK_IMPLEMENTATION=1 -DINSIDE_BLINK -DENABLE_IPC_FUZZER -DWEBP_EXTERN=extern -DUSE_EGL -DGTEST_API_= -DGTEST_HAS_POSIX_RE=0 -DGTEST_LANG_CXX11=1 -DGTEST_HAS_TR1_TUPLE=0 -DGOOGLE_PROTOBUF_NO_RTTI -DGOOGLE_PROTOBUF_NO_STATIC_INITIALIZER -DHAVE_PTHREAD -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 -DSK_GPU_WORKAROUNDS_HEADER=\"gpu/config/gpu_driver_bug_workaround_autogen.h\" -DSK_BUILD_FOR_MAC -DUSE_LIBJPEG_TURBO=1 -DWEBRTC_NON_STATIC_TRACE_EVENT_HANDLERS=0 -DGTEST_RELATIVE_PATH -DWEBRTC_CHROMIUM_BUILD -DWEBRTC_POSIX -DWEBRTC_MAC -DABSL_ALLOCATOR_NOTHROW=1 -DNO_MAIN_THREAD_WRAPPING -DLIBXSLT_STATIC -DUNIT_TEST -I../.. -Igen -I../../third_party/libwebp/src -I../../third_party/khronos -I../../gpu -I../../third_party/libyuv/include -I../../third_party/googletest/custom -I../../third_party/googletest/src/googletest/include -I../../third_party/protobuf/src -I../../third_party/protobuf/src -Igen/protoc_out -I../../third_party/boringssl/src/include -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/gpu -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/src/gpu -I../../third_party/skia/src/sksl -I../../third_party/angle/include -I../../third_party/angle/src/common/third_party/base -Igen/angle -I../../third_party/libjpeg_turbo -I../../v8/include -Igen/v8/include -I../../third_party/webrtc_overrides -I../../third_party/webrtc -I../../third_party/iccjpeg -I../../third_party/libpng -I../../third_party/zlib -I../../third_party/ots/include -I../../v8/include -Igen/v8/include -I../../third_party/libxml/src/include -I../../third_party/libxml/mac/include -I../../third_party/libxslt/src -I../../third_party/snappy/src -I../../third_party/snappy/mac -I../../third_party/googletest/custom -I../../third_party/googletest/src/googlemock/include -fno-strict-aliasing -fstack-protector -Wno-builtin-macro-redefined -D__DATE__= -D__TIME__= -D__TIMESTAMP__= -fcolor-diagnostics -fmerge-all-constants -Xclang -mllvm -Xclang -instcombine-lower-dbg-declare=0 -no-canonical-prefixes -arch x86_64 -Wall -Werror -Wextra -Wimplicit-fallthrough -Wthread-safety -Wunguarded-availability -Wno-missing-field-initializers -Wno-unused-parameter -Wno-c++11-narrowing -Wno-covered-switch-default -Wno-unneeded-internal-declaration -Wno-undefined-var-template -Wno-address-of-packed-member -Wno-nonportable-include-path -Wno-user-defined-warnings -Wno-unused-lambda-capture -Wno-null-pointer-arithmetic -Wno-enum-compare-switch -Wno-ignored-pragma-optimize -O2 -fno-omit-frame-pointer -gdwarf-2 -isysroot ../../build/mac_files/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk -mmacosx-version-min=10.9.0 -fvisibility=hidden -Xclang -load -Xclang ../../third_party/llvm-build/Release+Asserts/lib/libFindBadConstructs.dylib -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 -Wheader-hygiene -Wstring-conversion -Wtautological-overlap-compare -Xclang -load -Xclang ../../third_party/llvm-build/Release+Asserts/lib/libBlinkGCPlugin.dylib -Xclang -add-plugin -Xclang blink-gc-plugin -isystem ../../third_party/abseil-cpp -DLIBXML_STATIC= -Wno-inconsistent-missing-override -std=c++14 -stdlib=libc++ -fno-exceptions -fno-rtti -fvisibility-inlines-hidden -c ../../third_party/blink/renderer/core/animation/animation_sim_test.cc -o obj/third_party/blink/renderer/core/unit_tests/animation_sim_test.o
In file included from ../../third_party/blink/renderer/core/animation/animation_sim_test.cc:14:
In file included from ../../third_party/blink/renderer/core/testing/sim/sim_test.h:10:
In file included from ../../third_party/blink/renderer/core/frame/frame_test_helpers.h:40:
../../content/renderer/gpu/render_widget_compositor.h:24:10: fatal error: 'content/common/render_frame_metadata.mojom.h' file not found
#include "content/common/render_frame_metadata.mojom.h"
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.


Broke the main waterfall.

That include was added in https://chromium.googlesource.com/chromium/src/+/a2ff4f82109df55045dee9f54985a98054f86dc4


render_widget_compositor.h is in content/renderer:renderer. 

The mojo header is generated by content/common:mojo_bindings.

From what I can tell, the former has no public_deps on the latter.