content_unittests is flaking under MSan with the following error:

WebDataConsumerHandleImplTest.ReadData (run #1):
[ RUN      ] WebDataConsumerHandleImplTest.ReadData
==31922==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0xad5d8cb in UpdateSignalsStateNoLock mojo/edk/system/data_pipe_producer_dispatcher.cc:508:32
    #1 0xad5fbe6 in OnPortStatusChanged mojo/edk/system/data_pipe_producer_dispatcher.cc:489:3
    #2 0xad5fbe6 in OnPortStatusChanged mojo/edk/system/data_pipe_producer_dispatcher.cc:64:0
    #3 0xad7b6ab in PortStatusChanged mojo/edk/system/node_controller.cc:575:5
    #4 0xadaa45d in OnUserMessage mojo/edk/system/ports/node.cc:552:5
    #5 0xada947b in AcceptMessage mojo/edk/system/ports/node.cc:347:14
    #6 0xada74cf in SendMessage mojo/edk/system/ports/node.cc:334:12
    #7 0xad760aa in SendMessage mojo/edk/system/node_controller.cc:178:12
    #8 0xad59576 in SendDataPipeControlMessage mojo/edk/system/data_pipe_control_message.cc:27:12
    #9 0xad54936 in NotifyRead mojo/edk/system/data_pipe_consumer_dispatcher.cc:494:3
    #10 0xad54936 in ReadData mojo/edk/system/data_pipe_consumer_dispatcher.cc:197:0
    #11 0xad4ffab in ReadData mojo/edk/system/core.cc:767:10
    #12 0x5d6b4c4 in ReadDataRaw mojo/public/cpp/system/data_pipe.h:110:10
    #13 0x5d6b4c4 in read content/child/web_data_consumer_handle_impl.cc:61:0
    #14 0x3ce0d5e in ReadData content/child/web_data_consumer_handle_impl_unittest.cc:89:12
    #15 0x848eaf7 in Run base/callback.h:397:12
    #16 0x848eaf7 in RunTask base/debug/task_annotator.cc:51:0
    #17 0x82d7647 in RunTask base/message_loop/message_loop.cc:484:3
    #18 0x82d9047 in DeferOrRunPendingTask base/message_loop/message_loop.cc:493:5
    #19 0x82daa57 in DoWork base/message_loop/message_loop.cc:610:13
    #20 0x82e6c1a in Run base/message_loop/message_pump_default.cc:33:21
    #21 0x834098c in Run base/run_loop.cc:35:3
    #22 0x82d4c02 in ?? base/message_loop/message_loop.cc:300:3
    #23 0x83ceffa in ThreadMain base/threading/thread.cc:254:3
    #24 0x83be8db in ThreadFunc base/threading/platform_thread_posix.cc:70:3
    #25 0x7f269d4aae99 in start_thread /build/eglibc-rrybNj/eglibc-2.15/nptl/pthread_create.c:308:0
    #26 0x7f269ca2338c in ?? /build/eglibc-rrybNj/eglibc-2.15/misc/../sysdeps/unix/sysv/linux/x86_64/clone.S:112:0

  Uninitialized value was created by an allocation of 'port_status' in the stack frame of function '_ZN4mojo3edk26DataPipeProducerDispatcher24UpdateSignalsStateNoLockEv'
    #0 0xad5cf30 in UpdateSignalsStateNoLock mojo/edk/system/data_pipe_producer_dispatcher.cc:492:0

SUMMARY: MemorySanitizer: use-of-uninitialized-value (/tmp/runU2JWq0/out/Release/content_unittests+0xad5d8cb)
Exiting

https://build.chromium.org/p/chromium.memory.fyi/builders/Linux%20MSan%20Tests/builds/15658