Around 9PM on 8/17/16 testDontStopEachOther started failing pretty consistently on Jelly Bean.
https://test-results.appspot.com/dashboards/flakiness_dashboard.html#tests=org.chromium.content.browser.MediaSessionTest%23testDontStopEachOther&testType=content_shell_test_apk

Change list: https://chromium.googlesource.com/chromium/src/+log/60fb40258dc3548735720b48a5a8cfad8c11ecbd%5E..1cfa4f01c043a0da4dfff5594bb80b6a63d6e9fb?pretty=fuller
Maybe the change "Use the process-level MojoShellConnection to connect to mojo:media" was involved?

First failure: https://build.chromium.org/p/chromium.android/builders/Jelly%20Bean%20Tester/builds/5534

C  345.402s Main  [FAIL] org.chromium.content.browser.MediaSessionTest#testDontStopEachOther:
C  345.402s Main  junit.framework.AssertionFailedError: Criteria not met in allotted time.
C  345.402s Main  	at org.chromium.content.browser.test.util.CriteriaHelper.pollInstrumentationThread(CriteriaHelper.java:74)
C  345.402s Main  	at org.chromium.content.browser.test.util.DOMUtils.waitForMediaPlay(DOMUtils.java:105)
C  345.403s Main  	at org.chromium.content.browser.MediaSessionTest.testDontStopEachOther(MediaSessionTest.java:113)
C  345.403s Main  	at java.lang.reflect.Method.invokeNative(Native Method)
C  345.403s Main  	at android.test.InstrumentationTestCase.runMethod(InstrumentationTestCase.java:214)
C  345.403s Main  	at android.test.InstrumentationTestCase.runTest(InstrumentationTestCase.java:199)
C  345.403s Main  	at android.test.ActivityInstrumentationTestCase2.runTest(ActivityInstrumentationTestCase2.java:192)
C  345.403s Main  	at org.chromium.content_shell_apk.ContentShellTestBase.runTest(ContentShellTestBase.java:233)
C  345.403s Main  	at org.chromium.base.test.BaseTestResult.runParameterized(BaseTestResult.java:161)
C  345.403s Main  	at org.chromium.base.test.BaseTestResult.run(BaseTestResult.java:124)
C  345.403s Main  	at android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:191)
C  345.404s Main  	at android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:176)
C  345.404s Main  	at android.test.InstrumentationTestRunner.onStart(InstrumentationTestRunner.java:554)
C  345.404s Main  	at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:1701)