looks like this is a new recently added test https://codereview.chromium.org/1839283002. I am going to disable it for now.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/455971d846f277bdc7365eef1afd766fdd6d0d5d

commit 455971d846f277bdc7365eef1afd766fdd6d0d5d
Author: timvolodine <timvolodine@chromium.org>
Date: Thu Apr 07 11:27:49 2016

Disable cronet instrumentation test DiskStorageTest#testPurgeOldVersion

The test is crashing on Android Cronet Builder (dbg).

BUG= 601409 
TBR=yusufo@chromium.org,xunjieli@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/1865833004

Cr-Commit-Position: refs/heads/master@{#385711}

[modify] https://crrev.com/455971d846f277bdc7365eef1afd766fdd6d0d5d/components/cronet/android/test/javatests/src/org/chromium/net/DiskStorageTest.java

hmm now also failing the testReadOnlyStorageDirectory test:
C  130.789s Main  [  FAILED  ] org.chromium.net.DiskStorageTest#testReadOnlyStorageDirectory (CRASHED)
C  130.789s Main  
C  130.789s Main  1 FAILED TEST

https://uberchromegw.corp.google.com/i/chromium.android/builders/Android%20Cronet%20Builder%20%28dbg%29/builds/1652

adding infra, might be interesting to check the state of device just to be sure it's not a hardware issue..

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6a60a3936bc02d439fd57a0ee334be3bae820a4a

commit 6a60a3936bc02d439fd57a0ee334be3bae820a4a
Author: timvolodine <timvolodine@chromium.org>
Date: Thu Apr 07 13:17:54 2016

[Android] disable cronet instrumentation test DiskStorageTest#testReadOnlyStorageDirectory

Currently failing on Android Cronet Builder (dbg)
https://uberchromegw.corp.google.com/i/chromium.android/builders/Android%20Cronet%20Builder%20%28dbg%29/builds/1652

BUG= 601409 
TBR=yusufo@chromium.org,xunjieli@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/1866283003

Cr-Commit-Position: refs/heads/master@{#385735}

[modify] https://crrev.com/6a60a3936bc02d439fd57a0ee334be3bae820a4a/components/cronet/android/test/javatests/src/org/chromium/net/DiskStorageTest.java

Thanks, timvolodine@! I am working on it. It was due to a use-after-free bug.