Revision range first seen: As far as the bot's history goes, oldest available run (200th): https://uberchromegw.corp.google.com/i/chromium.perf/builders/Mac%20HDD%20Perf%20%283%29/builds/905 
Link to failing step log: https://uberchromegw.corp.google.com/i/chromium.perf/builders/Mac%20HDD%20Perf%20%283%29/builds/1099/steps/tab_switching.five_blank_pages/logs/stdio


[ RUN      ] blank_page.html
(INFO) 2016-03-17 13:44:05,049 desktop_browser_backend.HasBrowserFinishedLaunching:259  Discovered ephemeral port 60988
(WARNING) 2016-03-17 13:44:05,053 shared_page_state._TryCaptureScreenShot:157  Exception when trying to capture screenshot: AttributeError("'NoneType' object has no attribute 'browser'",)
(INFO) 2016-03-17 13:44:05,053 exception_formatter.PrintFormattedException:20  Try printing formatted exception: None None None

Telemetry Error during multi tab test:

Traceback (most recent call last):
  RunStory at third_party/catapult/telemetry/telemetry/page/shared_page_state.py:328
    self._PreparePage()
  _PreparePage at third_party/catapult/telemetry/telemetry/page/shared_page_state.py:298
    self._current_tab = self._test.TabForPage(self._current_page, self.browser)
  TabForPage at tools/perf/measurements/tab_switching.py:57
    return browser.tabs.New()
  New at third_party/catapult/telemetry/telemetry/internal/browser/tab_list.py:9
    return self._tab_list_backend.New(timeout)
  New at third_party/catapult/telemetry/telemetry/internal/backends/chrome/tab_list_backend.py:42
    return self.GetBackendFromContextId(context_id)
  GetBackendFromContextId at third_party/catapult/telemetry/telemetry/internal/backends/chrome_inspector/inspector_backend_list.py:78
    raise e
TimeoutException: 
********************************************************************************
(/b/build/slave/Mac_HDD_Perf__3_/build/src/third_party/catapult/telemetry/telemetry/internal/backends/chrome_inspector/inspector_backend.py:315 _ConvertExceptionFromInspectorWebsocket) The app is probably crashed:

Stack Trace:
********************************************************************************
	No crash dump found.
********************************************************************************
Standard output:
********************************************************************************
	2016-03-17 13:43:03.963 Google Chrome[15038:88986] NSWindow warning: adding an unknown subview: <FullSizeContentView: 0x7fa250eecfa0>
	2016-03-17 13:43:03.963 Google Chrome[15038:88986] Call stack:
	(
	    "+callStackSymbols disabled for performance reasons"
	)
	[15038:1299:0317/134304:ERROR:shell.cc(302)] Error: Instance: exe:chrome attempting to register an instance for a process it created for target: exe:chrome_renderer without the mojo:shell{client_process} capability class.
	<<<< VTVideoEncoderSelection >>>> VTSelectAndCreateVideoEncoderInstanceInternal: no video encoder found for 'avc1'
	
	[20:43:04.627] VTSelectAndCreateVideoEncoderInstanceInternal signalled err=-12908 (err) (Video encoder not available) at /SourceCache/CoreMedia_frameworks/CoreMedia-1562.238/Sources/VideoToolbox/VTVideoEncoderSelection.c line 1245
	[20:43:04.627] VTCompressionSessionCreate signalled err=-12908 (err) (Could not select and open encoder instance) at /SourceCache/CoreMedia_frameworks/CoreMedia-1562.238/Sources/VideoToolbox/VTCompressionSession.c line 946
	[15038:1299:0317/134305:ERROR:shell.cc(302)] Error: Instance: exe:chrome attempting to register an instance for a process it created for target: exe:chrome_renderer without the mojo:shell{client_process} capability class.
********************************************************************************
********************************************************************************
(/b/build/slave/Mac_HDD_Perf__3_/build/src/third_party/catapult/telemetry/telemetry/internal/backends/chrome_inspector/inspector_backend.py:320 _ConvertExceptionFromInspectorWebsocket) Original exception:
timed out
********************************************************************************
(/b/build/slave/Mac_HDD_Perf__3_/build/src/third_party/catapult/telemetry/telemetry/internal/backends/chrome_inspector/inspector_backend.py:341 _AddDebuggingInformation) Received a socket error in the browser connection and the tab still exists. The operation probably timed out.
********************************************************************************
(/b/build/slave/Mac_HDD_Perf__3_/build/src/third_party/catapult/telemetry/telemetry/internal/backends/chrome_inspector/inspector_backend.py:342 _AddDebuggingInformation) Debugger url: ws://127.0.0.1:60988/devtools/page/1030C824-E302-47D8-8C85-FFC3A836E0E0
********************************************************************************
(/b/build/slave/Mac_HDD_Perf__3_/build/src/third_party/catapult/telemetry/telemetry/internal/backends/chrome/tab_list_backend.py:110 _HandleDevToolsConnectionError) The browser exists and can be reached. The devtools target probably crashed.

Locals:
  context_id : u'1030C824-E302-47D8-8C85-FFC3A836E0E0'
  e          : TimeoutException('',)

Traceback (most recent call last):
  File "/b/build/slave/Mac_HDD_Perf__3_/build/src/third_party/catapult/telemetry/telemetry/internal/story_runner.py", line 84, in _RunStoryAndProcessErrorIfNeeded
    state.RunStory(results)
  File "/b/build/slave/Mac_HDD_Perf__3_/build/src/third_party/catapult/telemetry/telemetry/page/shared_page_state.py", line 340, in RunStory
    raise page_test.MultiTabTestAppCrashError
MultiTabTestAppCrashError

(INFO) 2016-03-17 13:44:05,151 power.Close:104  Closing power monitors
(INFO) 2016-03-17 13:44:05,152 platform.IsMonitoringPower:299  IsMonitoringPower: False
[  FAILED  ] blank_page.html (60231 ms)


Since the test fails less than one out of five times (2 failures in the last 20 runs, ~35 failures in the last 200 runs), I'm not disabling it now (https://chromium.googlesource.com/chromium/src/+/master/tools/perf/docs/perf_bot_sheriffing.md#testfailures).

nednguyen: It seems that jeremy@, who added the test (https://codereview.chromium.org/178363005), is not working on Chromium anymore. Could you please help me route this to the appropriate person? Thanks!

If the test is disabled, please downgrade to Pri-2.