GN CONFIG:
is_asan = true
enable_nacl = false  # Necessary until NaCl GN build is more complete.
is_component_build=true # The key to repro this bug.

BUILD TARGET:
webkit_unit_tests

RUN
webkit_unit_tests --gtest_filter=VideoPainterTestForSPv2.VideoLayerAppearsInLayerTree
or 
webkit_unit_tests --gtest_filter=HTMLVideoElementTest.setBufferingStrategy_NonUserPause
or
webkit_unit_tests --gtest_filter=HTMLVideoElementTest.setBufferingStrategy_UserPause


OBSERVE:
==20907==ERROR: AddressSanitizer: odr-violation (0x7f64a054f0a0):
  [1] size=37 'blink::mojom::blink::OffscreenCanvasSurface::Name_' gen/third_party/WebKit/public/platform/modules/offscreencanvas/offscreen_canvas_surface.mojom-blink.cc:57:36
  [2] size=37 'blink::mojom::blink::OffscreenCanvasSurface::Name_' gen/third_party/WebKit/public/platform/modules/offscreencanvas/offscreen_canvas_surface.mojom-blink.cc:57:36
These globals were registered at these points:
  [1]:
    #0 0x639e87  (/ssd/blink3/src/out/Asan/webkit_unit_tests+0x639e87)
    #1 0x7f649e56404b  (/ssd/blink3/src/out/Asan/./libblink_core.so+0x4e6604b)

  [2]:
    #0 0x639e87  (/ssd/blink3/src/out/Asan/webkit_unit_tests+0x639e87)
    #1 0x7f6497a1137b  (/ssd/blink3/src/out/Asan/./libblink_platform.so+0xc6337b)


We expect that tests should pass when run as asan + component. Toggling is_component_build to false will cause the test to pass, so I believe this is just a GN configuration error. 

Brett, tentatively assigning to you, seeing you touched relevant parts of the core/BUILD.gn recently.