Revision range first seen: https://build.chromium.org/p/chromium.perf/builders/Win%207%20Low-End%20Perf%20%282%29/builds/3263
Link to failing step log: https://build.chromium.org/p/chromium.perf/builders/Win%207%20Low-End%20Perf%20%282%29/builds/3427/steps/smoothness.tough_animation_cases/logs/stdio

In all cases, the failures have the following output:

[ RUN      ] overlay_background_color_css_transitions.html
(INFO) 2016-03-13 04:25:47,107 desktop_browser_backend._TryCooperativeShutdown:558  Successfully shut down browser cooperatively
(INFO) 2016-03-13 04:25:47,122 desktop_browser_backend.GetBrowserStartupArgs:272  Requested remote debugging port: 0
(INFO) 2016-03-13 04:25:47,122 desktop_browser_backend.Start:306  Starting Chrome ['C:\\b\\build\\slave\\Win_7_Low-End_Perf__2_\\build\\src\\out\\Release\\chrome.exe', u'--force-fieldtrial-params=AutomaticTabDiscarding.Enabled_Once_5:MinimumProtectionTime/300,SafeBrowsingUnverifiedDownloads.DisableByParameterMostSbTypes2:blacklist/%2Eexe-%2C%2Ezip-/block_sb_types/true/whitelist/%2Erar%2C%2Esvg%2C%2Eurl%2C%2Exml%2C%2Ezip,VarationsServiceControl.Interval_30min:fetch_period_min/30,PreRead.NoPrefetchArgument:NoPrefetchArgument/true,NetworkQualityEstimator.Enabled:Ethernet%2EDefaultMedianRTTMsec/106/4G%2EDefaultMedianKbps/1756/4G%2EDefaultMedianRTTMsec/159/None%2EDefaultMedianRTTMsec/272/2G%2EDefaultMedianRTTMsec/1337/3G%2EDefaultMedianKbps/658/3G%2EDefaultMedianRTTMsec/297/Bluetooth%2EDefaultMedianRTTMsec/135/Unknown%2EDefaultMedianKbps/1916/2G%2EDefaultMedianKbps/81/Unknown%2EDefaultMedianRTTMsec/121/None%2EDefaultMedianKbps/567/Bluetooth%2EDefaultMedianKbps/449/WiFi%2EDefaultMedianRTTMsec/168/Ethernet%2EDefaultMedianKbps/3263/WiFi%2EDefaultMedianKbps/2736/HalfLifeSeconds/60,ReportCertificateErrors.ShowAndPossiblySend:sendingThreshold/1%2E0,DataReductionProxyConfigService.Enabled:minimum_refresh_interval_on_success_msec/21600000,SafeBrowsingUpdateFrequency.UpdateTime15m:NextUpdateIntervalInMinutes/15,AutofillProfileOrderByFrecency.EnabledLimitTo3:limit/3', '--enable-gpu-benchmarking', u'--force-fieldtrials=SpdyEnableDependencies/Enable/ChildAccountDetection/Disabled/SdchPersistence/Enabled/InstanceID/Enabled/EnableSessionCrashedBubbleUI/Enabled/AutomaticTabDiscarding/Enabled_Once_5/AutofillFieldMetadata/Enabled/StrictSecureCookies/Enabled/SyncHttpContentCompression/Enabled/GoogleNow/Enable/SafeBrowsingReportPhishingErrorLink/Enabled/ChromotingQUIC/Enabled/TabSyncByRecency/Enabled/SafeBrowsingUnverifiedDownloads/DisableByParameterMostSbTypes2/VarationsServiceControl/Interval_30min/PageRevisitInstrumentation/Enabled/PasswordBranding/SmartLockBrandingSavePromptOnly/EnableGoogleCachedCopyTextExperiment/Button/RefreshTokenDeviceId/Enabled/WebRTC-H264WithOpenH264FFmpeg/Enabled/MaterialDesignDownloads/Enabled/PreRead/NoPrefetchArgument/WebRTC-LocalIPPermissionCheck/Enabled/ResourcePriorities/AllExceptAsyncScripts_11011_1_1_10/WebFontsIntervention/Enabled/use-new-media-cache/Enabled/ChromeDashboard/Enabled/LocalNTPSuggestionsService/Enabled/NetworkQualityEstimator/Enabled/SettingsEnforcement/enforce_always_with_extensions_and_dse/CaptivePortalInterstitial/Enabled/IntelligentSessionRestore/Enabled/OfferUploadCreditCards/Enabled/TriggeredResetFieldTrial/On/SchedulerExpensiveTaskBlocking/Enabled/ReportCertificateErrors/ShowAndPossiblySend/DataReductionProxyConfigService/Enabled/NewProfileManagement/Enabled/ExtensionContentVerification/Enforce/RenderingPipelineThrottling/Enabled/IconNTP/Default/ExtensionInstallVerification/Enforce/AutofillClassifier/Enabled/WebRTC-PeerConnectionDTLS1.2/Enabled/BrowserBlacklist/Enabled/PasswordGeneration/Disabled/SRTPromptFieldTrial/On/QUIC/Enabled/ExtensionActionRedesign/Enabled/SafeBrowsingUpdateFrequency/UpdateTime15m/AutofillProfileOrderByFrecency/EnabledLimitTo3', '--running-performance-benchmark', u'--enable-features=WebRTC-H264WithOpenH264FFmpeg,use-new-media-cache', '--touch-events=enabled', '--enable-net-benchmarking', '--metrics-recording-only', '--no-default-browser-check', '--no-first-run', '--enable-gpu-benchmarking', '--disable-background-networking', '--no-proxy-server', '--disable-component-extensions-with-background-pages', '--disable-default-apps', '--remote-debugging-port=0', '--enable-crash-reporter-for-testing', '--window-size=1280,1024', '--user-data-dir=c:\\users\\chrome~1.per\\appdata\\local\\temp\\tmp8jumio', 'about:blank']
(INFO) 2016-03-13 04:25:47,305 desktop_browser_backend.HasBrowserFinishedLaunching:259  Discovered ephemeral port 58397
Traceback (most recent call last):
  File "C:\b\build\slave\Win_7_Low-End_Perf__2_\build\src\third_party\catapult\telemetry\telemetry\internal\story_runner.py", line 77, in _RunStoryAndProcessErrorIfNeeded
    state.WillRunStory(story)
  File "C:\b\build\slave\Win_7_Low-End_Perf__2_\build\src\third_party\catapult\telemetry\telemetry\page\shared_page_state.py", line 269, in WillRunStory
    self.browser.tabs[0].WaitForDocumentReadyStateToBeComplete()
  File "C:\b\build\slave\Win_7_Low-End_Perf__2_\build\src\third_party\catapult\telemetry\telemetry\internal\browser\web_contents.py", line 61, in WaitForDocumentReadyStateToBeComplete
    'document.readyState == "complete"', timeout)
  File "C:\b\build\slave\Win_7_Low-End_Perf__2_\build\src\third_party\catapult\telemetry\telemetry\internal\browser\web_contents.py", line 111, in WaitForJavaScriptExpression
    e.message + '\n' + debug_message)
TimeoutException: 
Exception thrown when trying to capture console output: TimeoutException('',)

[  FAILED  ] overlay_background_color_css_transitions.html (100814 ms)

Note that the failures are happening in various tests (NOT only overlay_background_color_css_transitions.html).

Since failures are now much more common than non-failures (https://uberchromegw.corp.google.com/i/chromium.perf/builders/Win%207%20Low-End%20Perf%20%282%29), I'll disable the benchmark. Once it's disabled, I'll downgrade this issue to Pri-2 and assign it to the test owner.