Tryjobs are failing intermittently on linux_chromium_chromeos_rel_ng due to random compile failures in Blink's accessibility code. Here are a couple of random failures:

https://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_chromeos_rel_ng/builds/176202
https://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_chromeos_rel_ng/builds/176184
https://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_chromeos_rel_ng/builds/176173

In all cases the error is the same:

FAILED: /b/build/goma/gomacc ../../third_party/llvm-build/Release+Asserts/bin/clang++ -Wl,-z,now -Wl,-z,relro -Wl,--fatal-warnings -Wl,-z,defs -pthread -Wl,-z,noexecstack -fPIC -fuse-ld=gold -B/b/build/slave/linux_chromeos/build/src/third_party/binutils/Linux_x64/Release/bin -Wl,--disable-new-dtags -L. -Wl,-uIsHeapProfilerRunning,-uProfilerStart -Wl,-u_Z21InitialMallocHook_NewPKvj,-u_Z22InitialMallocHook_MMapPKvS0_jiiix,-u_Z22InitialMallocHook_SbrkPKvi -Wl,-u_Z21InitialMallocHook_NewPKvm,-u_Z22InitialMallocHook_MMapPKvS0_miiil,-u_Z22InitialMallocHook_SbrkPKvl -Wl,-u_ZN15HeapLeakChecker12IgnoreObjectEPKv,-u_ZN15HeapLeakChecker14UnIgnoreObjectEPKv -m64 -Wl,--gdb-index -Wl,--icf=all -Wl,-O1 -Wl,--as-needed -Wl,--gc-sections -o media_blink_unittests -Wl,--start-group obj/media/blink/media_blink_unittests.buffered_data_source_host_impl_unittest.o obj/media/blink/media_blink_unittests.buffered_data_source_unittest.o obj/media/blink/media_blink_unittests.buffered_resource_loader_unittest.o obj/media/blink/media_blink_unittests.cache_util_unittest.o obj/media/blink/media_blink_unittests.interval_map_unittest.o obj/media/blink/media_blink_unittests.key_system_config_selector_unittest.o obj/media/blink/media_blink_unittests.lru_unittest.o obj/media/blink/media_blink_unittests.mock_weburlloader.o obj/media/blink/media_blink_unittests.multibuffer_data_source_unittest.o obj/media/blink/media_blink_unittests.multibuffer_unittest.o obj/media/blink/media_blink_unittests.resource_multibuffer_data_provider_unittest.o obj/media/blink/media_blink_unittests.run_all_unittests.o obj/media/blink/media_blink_unittests.test_response_generator.o obj/media/blink/media_blink_unittests.url_index_unittest.o obj/media/blink/media_blink_unittests.video_frame_compositor_unittest.o obj/media/blink/media_blink_unittests.webaudiosourceprovider_impl_unittest.o obj/media/blink/libmedia_blink.a obj/media/libmedia.a obj/media/libmedia_test_support.a obj/base/libbase.a obj/base/libtest_support_base.a obj/cc/libcc.a obj/cc/blink/libcc_blink.a obj/components/scheduler/libscheduler.a obj/components/scheduler/libscheduler_test_support.a obj/gin/libgin.a obj/net/libnet.a obj/testing/libgmock.a obj/testing/libgtest.a obj/ui/gfx/libgfx.a obj/ui/gfx/libgfx_geometry.a obj/ui/gfx/libgfx_test_support.a obj/url/liburl_lib.a obj/base/allocator/liballocator.a obj/base/third_party/dynamic_annotations/libdynamic_annotations.a obj/base/libbase_static.a obj/third_party/modp_b64/libmodp_b64.a obj/base/libsymbolize.a obj/base/libxdg_mime.a obj/base/third_party/libevent/libevent.a obj/cc/libcc_proto.a obj/third_party/protobuf/libprotobuf_lite.a obj/gpu/libcommand_buffer_client.a obj/gpu/libcommand_buffer_common.a obj/gpu/command_buffer/libgles2_utils.a obj/gpu/libcommand_buffer_service.a obj/gpu/libdisk_cache_proto.a obj/gpu/libgpu_config.a obj/third_party/re2/libre2.a obj/ui/gl/libgl_wrapper.a obj/skia/libskia_library.a obj/skia/libskia_opts.a obj/skia/libskia_opts_ssse3.a obj/skia/libskia_opts_sse41.a obj/skia/libskia_opts_sse42.a obj/skia/libskia_opts_avx.a obj/skia/libskia_opts_avx2.a obj/third_party/zlib/libchrome_zlib.a obj/third_party/zlib/libzlib_x86_simd.a obj/third_party/sfntly/libsfntly.a obj/third_party/icu/libicuuc.a obj/skia/libskia_chrome.a obj/ui/base/libui_base.a obj/ui/base/libui_data_pack.a obj/base/libbase_i18n.a obj/third_party/icu/libicui18n.a obj/third_party/brotli/libbrotli.a obj/net/libnet_quic_proto.a obj/crypto/libcrcrypto.a obj/third_party/boringssl/libboringssl.a obj/third_party/boringssl/libboringssl_asm.a obj/sdch/libsdch.a obj/ui/events/libevents.a obj/third_party/harfbuzz-ng/libharfbuzz-ng.a obj/third_party/libpng/libpng.a obj/third_party/libjpeg_turbo/libjpeg_turbo.a obj/third_party/libjpeg/libjpeg.a obj/ui/gfx/x/libgfx_x11.a obj/ui/events/libdom_keycode_converter.a obj/ui/events/libevents_base.a obj/ui/events/libgesture_detection.a obj/ui/events/devices/libevents_devices.a obj/ui/events/x/libevents_x.a obj/ui/events/platform/libevents_platform.a obj/ui/events/platform/x11/libx11_events_platform.a obj/chromeos/libchromeos.a obj/components/libcloud_policy_proto.a obj/components/libdevice_event_log_component.a obj/components/libonc_component.a obj/components/libproxy_config.a obj/components/libpref_registry.a obj/components/prefs/libprefs.a obj/components/libsignin_core_account_id.a obj/dbus/libdbus.a obj/google_apis/libgoogle_apis.a obj/third_party/libxml/libxml2.a obj/chromeos/libcryptohome_proto.a obj/chromeos/libpower_manager_proto.a obj/build/linux/libpci.a obj/third_party/libXNVCtrl/libXNVCtrl.a obj/third_party/smhasher/libcityhash.a obj/third_party/angle/src/libtranslator.a obj/third_party/angle/src/libtranslator_lib.a obj/third_party/angle/src/libpreprocessor.a obj/third_party/angle/src/libangle_common.a obj/gpu/libgles2_cmd_helper.a obj/gpu/libgpu_ipc.a obj/ipc/libipc.a obj/gpu/libgpu_ipc_common.a obj/third_party/libwebm/libwebm.a libyuv.a obj/third_party/opus/libopus.a obj/media/libshared_memory_support.a obj/third_party/ffmpeg/libffmpeg.a obj/third_party/ffmpeg/libffmpeg_yasm.a obj/third_party/libvpx/libvpx.a obj/third_party/libvpx/libvpx_intrinsics_mmx.a obj/third_party/libvpx/libvpx_intrinsics_sse2.a obj/third_party/libvpx/libvpx_intrinsics_ssse3.a obj/third_party/libvpx/libvpx_intrinsics_sse4_1.a obj/third_party/libvpx/libvpx_intrinsics_avx.a obj/third_party/libvpx/libvpx_intrinsics_avx2.a obj/device/udev_linux/libudev_linux.a obj/build/linux/libudev.a obj/media/libmedia_asm.a obj/third_party/WebKit/Source/platform/libblink_platform.a obj/third_party/WebKit/Source/wtf/libwtf.a obj/third_party/WebKit/Source/platform/libblink_common.a obj/third_party/WebKit/Source/platform/libblink_heap_asm_stubs.a obj/device/battery/libdevice_battery_mojo_bindings.a obj/gpu/libgles2_c_lib.a obj/mojo/libmojo_environment_chromium.a obj/mojo/libmojo_environment_chromium_impl.a obj/mojo/libmojo_message_pump_lib.a obj/mojo/libmojo_cpp_bindings.a obj/mojo/libmojo_system_impl.a obj/third_party/iccjpeg/libiccjpeg.a obj/third_party/libwebp/libwebp_dec.a obj/third_party/libwebp/libwebp_dsp.a obj/third_party/libwebp/libwebp_dsp_sse2.a obj/third_party/libwebp/libwebp_dsp_sse41.a obj/third_party/libwebp/libwebp_utils.a obj/third_party/libwebp/libwebp_demux.a obj/third_party/libwebp/libwebp_enc.a obj/third_party/ots/libots.a obj/third_party/woff2/libwoff2_dec.a obj/third_party/qcms/libqcms.a obj/v8/tools/gyp/libv8_base.a obj/v8/tools/gyp/libv8_libbase.a obj/v8/tools/gyp/libv8_external_snapshot.a obj/third_party/WebKit/Source/web/libblink_web.a obj/third_party/WebKit/Source/modules/libmodules.a obj/third_party/sqlite/libchromium_sqlite3.a obj/third_party/WebKit/Source/core/libwebcore_dom.a obj/third_party/libxslt/libxslt.a obj/third_party/WebKit/Source/core/libwebcore_html.a obj/third_party/WebKit/Source/core/libwebcore_remaining.a obj/third_party/WebKit/Source/core/libwebcore_rendering.a obj/third_party/WebKit/Source/core/libwebcore_svg.a obj/third_party/WebKit/Source/core/libwebcore_generated.a obj/third_party/snappy/libsnappy.a obj/gpu/blink/libgpu_blink.a obj/gpu/libgles2_implementation.a obj/gpu/libgl_in_process_context.a obj/gpu/skia_bindings/libgpu_skia_bindings.a obj/components/scheduler/libscheduler_common.a -Wl,--end-group  -lrt -ldl -lgmodule-2.0 -lgobject-2.0 -lgthread-2.0 -lglib-2.0 -lfontconfig -lfreetype -lpangocairo-1.0 -lcairo -lpangoft2-1.0 -lpango-1.0 -lnss3 -lnssutil3 -lsmime3 -lplds4 -lplc4 -lnspr4 -lresolv -lX11 -lXi -lXcursor -lXext -lXfixes -lXrender -ldbus-1 -lpthread -lm -lXcomposite -lasound -lz -lXdamage -lXtst
obj/third_party/WebKit/Source/modules/libmodules.a(obj/third_party/WebKit/Source/modules/accessibility/modules.AXNodeObject.o):../../third_party/WebKit/Source/modules/accessibility/AXNodeObject.cpp:function blink::AXNodeObject::isControllingVideoElement() const: error: undefined reference to 'blink::RuntimeEnabledFeatures::isMediaEnabled'
obj/third_party/WebKit/Source/modules/libmodules.a(obj/third_party/WebKit/Source/modules/accessibility/modules.AXNodeObject.o):../../third_party/WebKit/Source/modules/accessibility/AXNodeObject.cpp:function blink::ThreadState::vectorBackingHeap(unsigned long): error: undefined reference to 'blink::ThreadState::heapIndexOfVectorHeapLeastRecentlyExpanded(int, int)'
clang: error: linker command failed with exit code 1 (use -v to see invocation)
ninja: build stopped: subcommand failed.

Dominic, could you please investigate this? It's affecting the commit queue and needs to be resolved ASAP.