Example failure:

https://chromium-swarm.appspot.com/task?id=33c97693c6d76c10&refresh=10&show_raw=1


Exception raised when cleaning story run: 

Traceback (most recent call last):
_RunStoryAndProcessErrorIfNeeded at /b/s/w/ir_o3iPA/third_party/catapult/telemetry/telemetry/internal/story_runner.py:113
state.DidRunStory(results)
traced_function at /b/s/w/ir_o3iPA/third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py:75
return func(*args, **kwargs)
DidRunStory at /b/s/w/ir_o3iPA/third_party/catapult/telemetry/telemetry/page/shared_page_state.py:153
self._current_tab.Close()
traced_function at /b/s/w/ir_o3iPA/third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py:75
return func(*args, **kwargs)
Close at /b/s/w/ir_o3iPA/third_party/catapult/telemetry/telemetry/internal/browser/tab.py:100
self._tab_list_backend.CloseTab(self.id)
CloseTab at /b/s/w/ir_o3iPA/third_party/catapult/telemetry/telemetry/internal/backends/chrome/tab_list_backend.py:67
py_utils.WaitFor(lambda: tab_id not in self.IterContextIds(), timeout=5)
WaitFor at /b/s/w/ir_o3iPA/third_party/catapult/common/py_utils/py_utils/__init__.py:132
(timeout, GetConditionString()))
TimeoutException: Timed out while waiting 5s for py_utils.WaitFor(lambda: tab_id not in self.IterContextIds(), timeout=5).

Locals:
GetConditionString : <function GetConditionString at 0x7f92edd132a8>
condition : <function <lambda> at 0x7f92edd13140>
elapsed_time : 5.240896940231323
last_output_elapsed_time : 5.240896940231323
last_output_time : 1484731604.683701
now : 1484731609.924598
poll_interval : 0.5240896940231323
res : False
start_time : 1484731604.683701
timeout : 5