UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36
Platform: 9451.0.2017_04_11_0437 (Test Build) developer-build kevin

Steps to reproduce the problem:
1. Update to include "Fix flaky NPE in oobe.js." patches in chromium/src and third_party/catapult
2. Run any telemetry benchmark, like page_cycler_v2

What is the expected behavior?
Page cycler runs.

What went wrong?
I get the following error:

INFO:root:Invoking Oobe.loginForTesting
ERROR:root:Failure while starting browser backend.
Traceback (most recent call last):
  File "/work/google/chrome/src/third_party/catapult/telemetry/telemetry/internal/browser/browser.py", line 58, in __init__
    self._browser_backend.Start()
  File "/work/google/chrome/src/third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py", line 75, in traced_function
    return func(*args, **kwargs)
  File "/work/google/chrome/src/third_party/catapult/telemetry/telemetry/internal/backends/chrome/cros_browser_backend.py", line 163, in Start
    self._gaia_id, not self.browser_options.disable_gaia_services)
  File "/work/google/chrome/src/third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py", line 75, in traced_function
    return func(*args, **kwargs)
  File "/work/google/chrome/src/third_party/catapult/telemetry/telemetry/internal/backends/chrome/oobe.py", line 61, in NavigateFakeLogin
    enterprise_enroll)
  File "/work/google/chrome/src/third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py", line 75, in traced_function
    return func(*args, **kwargs)
  File "/work/google/chrome/src/third_party/catapult/telemetry/telemetry/internal/backends/chrome/oobe.py", line 41, in _ExecuteOobeApi
    "typeof Oobe == 'function' && Oobe.readyForTesting", timeout=120)
  File "/work/google/chrome/src/third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py", line 75, in traced_function
    return func(*args, **kwargs)
  File "/work/google/chrome/src/third_party/catapult/telemetry/telemetry/internal/browser/web_contents.py", line 191, in WaitForJavaScriptCondition
    return self._inspector_backend.WaitForJavaScriptCondition(*args, **kwargs)
  File "/work/google/chrome/src/third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py", line 75, in traced_function
    return func(*args, **kwargs)
  File "/work/google/chrome/src/third_party/catapult/telemetry/telemetry/internal/backends/chrome_inspector/inspector_backend.py", line 294, in WaitForJavaScriptCondition
    e.message + '\n' + debug_message)
TimeoutException: Timed out while waiting 120s for IsJavaScriptExpressionTrue.
Console output:
(warning) chrome://resources/polymer/v1_0/iron-flex-layout/classes/iron-shadow-flex-layout-extracted.js:1: This file is deprecated. Please use `iron-flex-layout/iron-flex-layout-classes.html`, and one of the specific dom-modules instead
(warning) chrome://resources/polymer/v1_0/iron-flex-layout/classes/iron-flex-layout-extracted.js:1: This file is deprecated. Please use `iron-flex-layout/iron-flex-layout-classes.html`, and one of the specific dom-modules instead
(error) chrome://oobe/oobe.js:8526: TypeError: Cannot read property 'addObserver' of null
    at HTMLDivElement.decorate (chrome://oobe/oobe.js:17267:19)
    at HTMLDivElement.initializeImpl_ (chrome://oobe/oobe.js:226:12)
    at HTMLDivElement.initialize (chrome://oobe/oobe.js:122:35)
    at Object.api.register (chrome://oobe/oobe.js:435:18)
    at Function.initialize (chrome://oobe/oobe.js:17956:32)
    at HTMLDocument.<anonymous> (chrome://oobe/oobe.js:8521:10)
(log) chrome://oobe/oobe.js:8034: Loading asset bundle oauth-enrollment
(log) chrome://oobe/oobe.js:8018: Finished loading asset bundle oauth-enrollment

Did this work before? Yes Anything prior to 9a55abab029cb9ae94f5160ded11b09a4638a955 (third_party/catapult)

Chrome version: 59.0.3068.0  Channel: n/a
OS Version: 9451.0
Flash Version: 

Reverting 9a55abab029cb9ae94f5160ded11b09a4638a955 (third_party/catapult) allows Telemetry to run as before. 

Is there something specifically wrong with my setup which means that Oobe.readyForTesting is not being set as it should? The build includes "Fix flaky NPE in oobe.js" in chromium/src.