Findit identified the culprit r552436 with confidence 100.0% in the config "chromium.memory / Linux ASan Tests (sandboxed)"
based on the flakiness trend:

https://findit-for-me.appspot.com/waterfall/flake?key=ag9zfmZpbmRpdC1mb3ItbWVyuAELEhdNYXN0ZXJGbGFrZUFuYWx5c2lzUm9vdCKBAWNocm9taXVtLm1lbW9yeS9MaW51eCBBU2FuIFRlc3RzIChzYW5kYm94ZWQpLzQ1NjY3L2Jyb3dzZXJfdGVzdHMvUTBSTlh6a3ZSVU5MUlc1amNubHdkR1ZrVFdWa2FXRlVaWE4wTGsxMWJIUnBjR3hsUTJSdFZIbHdaWE12TUE9PQwLEhNNYXN0ZXJGbGFrZUFuYWx5c2lzGAEM


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I'll take a look.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ad680907edd75864926df6f07e7485840aa6bffa

commit ad680907edd75864926df6f07e7485840aa6bffa
Author: Xiaohan Wang <xhwang@chromium.org>
Date: Sat Apr 21 06:53:29 2018

media: Fix ECKEncryptedMediaTest.MultipleCdmTypes test

When session 2 crashes, it crashes on KeyStatusUpdate, which is after
resolving the update promise in Clear Key CDM. Due to IPC and async
calls, by the time the crash happens, the JS update promise could have
been resolved, or rejected due to the crash.

This CL use "finally" instead of "then" so that we will continue the
test regardlss whether the session update that causes the crash is
resolved or rejected.

Tbr: jrummell@chromium.org
Bug:  835509 
Change-Id: I380546b2f6cf29e60d082c79f913f46fad4eaf0b
Reviewed-on: https://chromium-review.googlesource.com/1023370
Reviewed-by: Xiaohan Wang <xhwang@chromium.org>
Commit-Queue: Xiaohan Wang <xhwang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#552582}
[modify] https://crrev.com/ad680907edd75864926df6f07e7485840aa6bffa/media/test/data/multiple_cdm_types.html