The timeout happens roughly half of the time on both system_health.memory_desktop and system_health.memory_desktop.reference:

  https://build.chromium.org/p/chromium.perf/builders/Win%20Zenbook%20Perf%20%283%29/builds/1708/steps/system_health.memory_desktop.reference/logs/stdio
  https://build.chromium.org/p/chromium.perf/builders/Win%20Zenbook%20Perf%20%283%29/builds/1709/steps/system_health.memory_desktop/logs/stdio
  https://build.chromium.org/p/chromium.perf/builders/Win%20Zenbook%20Perf%20%283%29/builds/1710/steps/system_health.memory_desktop/logs/stdio
  https://build.chromium.org/p/chromium.perf/builders/Win%20Zenbook%20Perf%20%283%29/builds/1710/steps/system_health.memory_desktop.reference/logs/stdio
  https://build.chromium.org/p/chromium.perf/builders/Win%20Zenbook%20Perf%20%283%29/builds/1711/steps/system_health.memory_desktop.reference/logs/stdio

Error message:

  [ RUN      ] load:news:engadget
  (INFO) 2016-05-15 17:13:18,960 chrome_tracing_agent._CreateTraceConfigFile:243  Trace config file string: {"trace_config":{"excluded_categories": ["*"], "included_categories": ["disabled-by-default-memory-infra"], "record_mode": "record-as-much-as-possible"}}
  (INFO) 2016-05-15 17:13:18,960 tracing_backend.StartTracing:124  Start Tracing Request: {'params': {'transferMode': 'ReturnAsStream', 'options': 'record-as-much-as-possible', 'categories': 'disabled-by-default-memory-infra,-*'}, 'method': 'Tracing.start'}
  (INFO) 2016-05-15 17:13:18,976 cache_temperature.EnsurePageCacheTemperature:29  PageCacheTemperature: any
  Traceback (most recent call last):
    File "C:\b\build\slave\Win_Zenbook_Perf__3_\build\src\third_party\catapult\telemetry\telemetry\internal\story_runner.py", line 84, in _RunStoryAndProcessErrorIfNeeded
      state.RunStory(results)
    File "C:\b\build\slave\Win_Zenbook_Perf__3_\build\src\third_party\catapult\telemetry\telemetry\page\shared_page_state.py", line 330, in RunStory
      self._current_page.Run(self)
    File "C:\b\build\slave\Win_Zenbook_Perf__3_\build\src\third_party\catapult\telemetry\telemetry\page\__init__.py", line 99, in Run
      self.RunPageInteractions(action_runner)
    File "C:\b\build\slave\Win_Zenbook_Perf__3_\build\src\tools\perf\page_sets\system_health_stories.py", line 327, in RunPageInteractions
      action_runner.tab.WaitForDocumentReadyStateToBeComplete()
    File "C:\b\build\slave\Win_Zenbook_Perf__3_\build\src\third_party\catapult\telemetry\telemetry\internal\browser\web_contents.py", line 70, in WaitForDocumentReadyStateToBeComplete
      'document.readyState == "complete"', timeout)
    File "C:\b\build\slave\Win_Zenbook_Perf__3_\build\src\third_party\catapult\telemetry\telemetry\internal\browser\web_contents.py", line 136, in WaitForJavaScriptExpression
      e.message + '\n' + debug_message)
  TimeoutException: Timed out while waiting 90s for IsJavaScriptExpressionTrue.
  Console output:
  (error) http://images.taboola.com/taboola/image/fetch/dpr_2.0%2Cf_jpg%2Cq_80%2Ch_100%2Cw_100%2Cc_fill%2Cg_faces%2Ce_sharpen/http%3A//cdn.taboolasyndication.com/libtrc/static/thumbnails/ee497630ea5347d79b7f20c1b0e0e24d.png:0: Failed to load resource: the server responded with a status of 404 (Not Found)
  (error) http://images.taboola.com/taboola/image/fetch/dpr_2.0%2Cf_jpg%2Cq_80%2Ch_100%2Cw_100%2Cc_fill%2Cg_faces%2Ce_sharpen/http%3A//cdn.taboolasyndication.com/libtrc/static/thumbnails/da432e93d6c2e5984d803460b8dba344.jpg:0: Failed to load resource: the server responded with a status of 404 (Not Found)
  (error) http://images.taboola.com/taboola/image/fetch/dpr_2.0%2Cf_jpg%2Cq_80%2Ch_100%2Cw_100%2Cc_fill%2Cg_faces%2Ce_sharpen/http%3A//cdn.taboolasyndication.com/libtrc/static/thumbnails/72a34141e77037713627b8b90952bea2.png:0: Failed to load resource: the server responded with a status of 404 (Not Found)
  (log) http://cdn.taboola.com/libtrc/impl.208-RELEASE.js:2: Failed to load thumbnail http://images.taboola.com/taboola/image/fetch/dpr_2.0%2Cf_jpg%2Cq_80%2Ch_100%2Cw_100%2Cc_fill%2Cg_faces%2Ce_sharpen/http%3A//cdn.taboolasyndication.com/libtrc/static/thumbnails/ee497630ea5347d79b7f20c1b0e0e24d.png for item=~~V1~~5355901320667092574~~IVvjMkXupEMyEbbseNz4fKisxT4PTd8ZpsS2gCj3lAL8LmOS8JEBYC2Y-WT_71hBGIGDnafEpix4cV15yr27Lg, loading http://cdn.taboolasyndication.com/libtrc/static/thumbnails/ee497630ea5347d79b7f20c1b0e0e24d.png thumbnail instead
  (log) http://cdn.taboola.com/libtrc/impl.208-RELEASE.js:2: Failed to load thumbnail http://images.taboola.com/taboola/image/fetch/dpr_2.0%2Cf_jpg%2Cq_80%2Ch_100%2Cw_100%2Cc_fill%2Cg_faces%2Ce_sharpen/http%3A//cdn.taboolasyndication.com/libtrc/static/thumbnails/da432e93d6c2e5984d803460b8dba344.jpg for item=~~V1~~-5897964784149874403~~qGqJZncVOiSby1dX1PdLcs1lE-z-qHSdoIjYvonn3HjxYi68Go_kWwVZSiQHW14KGIGDnafEpix4cV15yr27Lg, loading http://cdn.taboolasyndication.com/libtrc/static/thumbnails/da432e93d6c2e5984d803460b8dba344.jpg thumbnail instead
  (log) http://cdn.taboola.com/libtrc/impl.208-RELEASE.js:2: Failed to load thumbnail http://images.taboola.com/taboola/image/fetch/dpr_2.0%2Cf_jpg%2Cq_80%2Ch_100%2Cw_100%2Cc_fill%2Cg_faces%2Ce_sharpen/http%3A//cdn.taboolasyndication.com/libtrc/static/thumbnails/72a34141e77037713627b8b90952bea2.png for item=~~V1~~-1462638005235033057~~ybQXnFDVFrtqAXOWZA33MGUcV6TCkPem_8rsf-GbVJCjFaS9oydxo-lEHimdkN41GIGDnafEpix4cV15yr27Lg, loading http://cdn.taboolasyndication.com/libtrc/static/thumbnails/72a34141e77037713627b8b90952bea2.png thumbnail instead
  (error) http://cdn.taboolasyndication.com/libtrc/static/thumbnails/da432e93d6c2e5984d803460b8dba344.jpg:0: Failed to load resource: the server responded with a status of 404 (Not Found)
  (error) http://cdn.taboolasyndication.com/libtrc/static/thumbnails/72a34141e77037713627b8b90952bea2.png:0: Failed to load resource: the server responded with a status of 404 (Not Found)
  (error) http://cdn.taboolasyndication.com/libtrc/static/thumbnails/ee497630ea5347d79b7f20c1b0e0e24d.png:0: Failed to load resource: the server responded with a status of 404 (Not Found)


  [  FAILED  ] load:news:engadget (130841 ms)

This happened to me once locally (Linux) as well. The next action is to disable Engadget in system_health.memory_desktop.