Hmm, why is it suddenly flaky:

https://test-results.appspot.com/dashboards/flakiness_dashboard.html#testType=media_base_junit_tests

java.lang.AssertionError: expected:<4800> but was:<5600>
	at org.junit.Assert.fail(Assert.java:88)
	at org.junit.Assert.failNotEquals(Assert.java:834)
	at org.junit.Assert.assertEquals(Assert.java:645)
	at org.junit.Assert.assertEquals(Assert.java:631)
	at org.chromium.media.AudioTrackOutputStreamTest.playPiecewiseBitstream(AudioTrackOutputStreamTest.java:183)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:52)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.robolectric.RobolectricTestRunner$HelperTestRunner$1.evaluate(RobolectricTestRunner.java:523)
	at org.robolectric.internal.SandboxTestRunner$2.evaluate(SandboxTestRunner.java:226)
	at org.robolectric.internal.SandboxTestRunner.runChild(SandboxTestRunner.java:108)
	at org.robolectric.internal.SandboxTestRunner.runChild(SandboxTestRunner.java:35)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.robolectric.internal.SandboxTestRunner$1.evaluate(SandboxTestRunner.java:62)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.chromium.testing.local.GtestComputer$GtestSuiteRunner.run(GtestComputer.java:48)
	at org.junit.runners.Suite.runChild(Suite.java:128)
	at org.junit.runners.Suite.runChild(Suite.java:27)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:115)
	at org.chromium.testing.local.JunitTestMain.main(JunitTestMain.java:105)

No changes in past 6 months, https://chromium.googlesource.com/chromium/src/+log/454bc4b98c3b4072c90bb9409e404d3f6dcde361/media/base/android/java/src/org/chromium/media/AudioTrackOutputStream.java

This isn't flaky enough to be Pri-0, only one of your flakes was this test. Looking at it though.

Patch here, https://chromium-review.googlesource.com/c/chromium/src/+/1163988

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9208abcaaba5422ee92c42a5a284d3960c4bc3f0

commit 9208abcaaba5422ee92c42a5a284d3960c4bc3f0
Author: Dale Curtis <dalecurtis@chromium.org>
Date: Mon Aug 06 20:07:00 2018

Bitstream audio test may get more OnMoreData calls than expected.

BUG= 871354 
TEST=none
TBR=tsunghung

Change-Id: I8134ea1476c7a25f9dc8d00dc1e62a4cd951ee93
Reviewed-on: https://chromium-review.googlesource.com/1163988
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580960}
[modify] https://crrev.com/9208abcaaba5422ee92c42a5a284d3960c4bc3f0/media/base/android/java/src/test/org/chromium/media/AudioTrackOutputStreamTest.java