Top-of-tree Chromium has the following compiler warnings on Windows at least, and in the component build at least. Seems clear they were introduced by https://codereview.chromium.org/2144623003 .

D:\src\chrome\src>ninja -j 200 -C out\Release chrome
ninja: Entering directory `out\Release'
[53/69] LINK(DLL) content.dll content.dll.lib content.dll.pdb
render_frame_host_impl.obj : warning LNK4217: locally defined symbol ?Create@SensorProviderImpl@device@@SAXV?$InterfaceRequest@VSensorProvider@mojom@device@@@mojo@@@Z (public: static void __cdecl devi
ce::SensorProviderImpl::Create(class mojo::InterfaceRequest<class device::mojom::SensorProvider>)) imported in function "private: void __cdecl content::RenderFrameHostImpl::RegisterMojoInterfaces(void
)" (?RegisterMojoInterfaces@RenderFrameHostImpl@content@@AEAAXXZ)
sensor.mojom.obj : warning LNK4217: locally defined symbol ??0PlatformSensorConfiguration@device@@QEAA@XZ (public: __cdecl device::PlatformSensorConfiguration::PlatformSensorConfiguration(void)) impor
ted in function "public: virtual bool __cdecl device::mojom::SensorStub::AcceptWithResponder(class mojo::Message *,class mojo::MessageReceiverWithStatus *)" (?AcceptWithResponder@SensorStub@mojom@devi
ce@@UEAA_NPEAVMessage@mojo@@PEAVMessageReceiverWithStatus@5@@Z)
sensor.mojom.obj : warning LNK4217: locally defined symbol ??1PlatformSensorConfiguration@device@@QEAA@XZ (public: __cdecl device::PlatformSensorConfiguration::~PlatformSensorConfiguration(void)) impo
rted in function "public: virtual bool __cdecl device::mojom::SensorStub::AcceptWithResponder(class mojo::Message *,class mojo::MessageReceiverWithStatus *)" (?AcceptWithResponder@SensorStub@mojom@dev
ice@@UEAA_NPEAVMessage@mojo@@PEAVMessageReceiverWithStatus@5@@Z)
sensor_struct_traits.obj : warning LNK4217: locally defined symbol ?set_frequency@PlatformSensorConfiguration@device@@QEAAXN@Z (public: void __cdecl device::PlatformSensorConfiguration::set_frequency(
double)) imported in function "public: static bool __cdecl mojo::StructTraits<class device::mojom::SensorConfiguration,class device::PlatformSensorConfiguration>::Read(class device::mojom::SensorConfi
gurationDataView,class device::PlatformSensorConfiguration *)" (?Read@?$StructTraits@VSensorConfiguration@mojom@device@@VPlatformSensorConfiguration@3@@mojo@@SA_NVSensorConfigurationDataView@mojom@dev
ice@@PEAVPlatformSensorConfiguration@5@@Z)