The pain started here: https://build.chromium.org/p/chromium.android/builders/Android%20Cronet%20Builder/builds/1675

C  123.028s Main  [==========] 286 tests ran.
C  123.028s Main  [  PASSED  ] 17 tests.
C  123.028s Main  [  FAILED  ] 269 tests, listed below:
C  123.028s Main  [  FAILED  ] org.chromium.net.BidirectionalStreamQuicTest#testQuicBidirectionalStreamDisabled (CRASHED)
C  123.028s Main  [  FAILED  ] org.chromium.net.BidirectionalStreamQuicTest#testSimpleGet (CRASHED)
C  123.028s Main  [  FAILED  ] org.chromium.net.BidirectionalStreamTest#testAddHeader (CRASHED)
C  123.028s Main  [  FAILED  ] org.chromium.net.BidirectionalStreamTest#testBadBuffers (CRASHED)
C  123.028s Main  [  FAILED  ] org.chromium.net.BidirectionalStreamTest#testBadHeaderName (CRASHED)
C  123.029s Main  [  FAILED  ] org.chromium.net.BidirectionalStreamTest#testBadHeaderValue (CRASHED)
C  123.029s Main  [  FAILED  ] org.chromium.net.BidirectionalStreamTest#testBadMethod (CRASHED)
C  123.029s Main  [  FAILED  ] org.chromium.net.BidirectionalStreamTest#testBuilderChecks (CRASHED)
C  123.029s Main  [  FAILED  ] org.chromium.net.BidirectionalStreamTest#testCronetEngineShutdown (CRASHED)
C  123.029s Main  [  FAILED  ] org.chromium.net.BidirectionalStreamTest#testCronetEngineShutdownAfterStreamCancel (CRASHED)
C  123.029s Main  [  FAILED  ] org.chromium.net.BidirectionalStreamTest#testCronetEngineShutdownAfterStreamFailure (CRASHED)
...

I'm suspecting something like r384010 or r384038 or maybe r384039.