CFI Linux Full bot is currently broken:
https://build.chromium.org/p/chromium.fyi/builders/CFI%20Linux%20Full/builds/357

In particular, BytesConsumerTeeTest of webkit_unit_tests is failing under CFI (https://www.chromium.org/developers/testing/control-flow-integrity) check:

Starting program: /usr/local/google/home/krasin/chr22/src/out/cfi-diag-tot/webkit_unit_tests --gtest_filter=BytesConsumerTeeTest.Error
Note: Google Test filter = BytesConsumerTeeTest.Error
[==========] Running 1 test from 1 test case.
[----------] Global test environment set-up.
[----------] 1 test from BytesConsumerTeeTest
[ RUN      ] BytesConsumerTeeTest.Error
[       OK ] BytesConsumerTeeTest.Error (3 ms)
[----------] 1 test from BytesConsumerTeeTest (3 ms total)

[----------] Global test environment tear-down
[==========] 1 test from 1 test case ran. (3 ms total)
[  PASSED  ] 1 test.
../../third_party/WebKit/Source/platform/heap/GCInfo.h:37:9: runtime error: control flow integrity check for type 'blink::BytesConsumerTestUtil::Reader' failed during cast to unrelated type (vtable address 0x000003404d30)
0x000003404d30: note: vtable is of type 'blink::BytesConsumerTestUtil::TwoPhaseReader'
 00 00 00 00  40 5c ad 00 00 00 00 00  00 ed ac 00 00 00 00 00  d0 5c ad 00 00 00 00 00  f0 ec ac 00
              ^ 
../../third_party/WebKit/Source/platform/heap/GarbageCollected.h:230:9: runtime error: control flow integrity check for type 'blink::BytesConsumerTestUtil::Reader' failed during base-to-derived cast (vtable address 0x000003404d30)
0x000003404d30: note: vtable is of type 'blink::BytesConsumerTestUtil::TwoPhaseReader'
 00 00 00 00  40 5c ad 00 00 00 00 00  00 ed ac 00 00 00 00 00  d0 5c ad 00 00 00 00 00  f0 ec ac 00

The test was introduced in https://codereview.chromium.org/2269953004

The bug is a copy-paste issue here:
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/modules/fetch/BytesConsumerTestUtil.h?sq=package:chromium&dr=CSs&l=107

class TwoPhaseReader final : public GarbageCollectedFinalized<Reader>, public BytesConsumer::Client

I will send a fix in a moment.