Example build:
https://build.chromium.org/p/chromium.fyi/builders/CrWinAsan/builds/3888/steps/compile/logs/stdio

[863/30651] RULE Compile assembly libavutil\x86\fixed_dsp.asm
FAILED: gen/third_party/ffmpeg/yasm/fixed_dsp.obj 
C:\b\depot_tools\python276_bin\python.exe gyp-win-tool action-wrapper environment.x86 ffmpeg_yasm_target_assemble_09ab246a61f84f7fef6ac74dbf1e639a.f2be5c7131fe239773328063673860bf.rsp ..\..\third_party\ffmpeg
==4148==ERROR: AddressSanitizer failed to allocate 0x16000000 (369098752) bytes at 0x3a000000 (error code: 1455)
==4148==ReserveShadowMemoryRange failed while trying to map 0x16000000 bytes. Perhaps you're using ulimit -v

The error code is 1455: ERROR_COMMITMENT_LIMIT, which means the builder is out of swap, probably because it is concurrently running a large number of ASan-instrumented yasm processes, each of which will allocate a large amount of shadow.

Can we increase the swap file size on the bot, or is that too much customization? We'll have to remember to do it again next time we add a new ASan builder.