This bot:https://build.chromium.org/p/chromium.perf/builders/Android%20Nexus5X%20WebView%20Perf%20%282%29

Is showing potentially flaky failures in power.tough_ad_cases. It has been red three builds in a row, but has shown flaky failures on this tes in the past.


The logs have no obvious causes in them, there's entries like:

	06-16 06:09:15.921 11590 12814 I X509Util: Failed to validate the certificate chain, error: java.security.cert.CertPathValidatorException: Trust anchor for certification path not found.
	
	06-16 06:09:16.723 11590 11590 W cr_BindingManager: Cannot call determinedVisibility() - never saw a connection for the pid: 11590


	06-16 05:52:28.230  5664  5664 I chromium: [INFO:CONSOLE(0)] "Uncaught (in promise) NotSupportedError: Failed to load because no supported source was found.", source: http://edition.cnn.com/2015/01/09/politics/nebraska-keystone-pipeline/index.html (0)
	06-16 05:52:28.238  5664  5664 I chromium: [INFO:CONSOLE(4)] "[CVP|_top|VideoPlayer|2750]", source: http://edition.i.cdn.cnn.com/.a/1.172.1/js/cnn-header-second.min.js (4)
	06-16 05:52:48.413  5601  5604 E chromium: [0616/055248:ERROR:socket.cc(342)] send: Broken pipe
	06-16 05:52:48.413  5601  5604 E chromium: [0616/055248:ERROR:socket.cc(319)] read: Bad file descriptor
	06-16 05:52:48.413  5601  5604 E chromium: [0616/055248:ERROR:command.cc(55)] Read() error, endpoint was unexpectedly closed.
	06-16 05:52:48.413  5601  5604 E chromium: [0616/055248:ERROR:socket.cc(342)] send: Bad file descriptor
	06-16 05:52:48.413  5601  5604 E chromium: [0616/055248:ERROR:device_listener.cc(100)] Host could not connect to server.
	06-16 05:52:48.413  5601  5604 E chromium: [0616/055248:ERROR:device_listener.cc(103)] Adb Control connection lost. Listener port: 38890
	06-16 05:52:49.386  5664  5664 I chromium: [INFO:CONSOLE(1)] "Interaction.ToughAd: 30039.626ms", source:  (1)
	
But I'm not sure if these are normal errors, side effects or actual causes.