Stack:
07/29 05:11:42.120 INFO |run_chromeos_tests:0052| [182/273] core.about_tracing_integration_test.AboutTracingIntegrationTest.testBasicTraceRecording failed unexpectedly 99.7608s:
07/29 05:11:42.121 INFO |run_chromeos_tests:0052|   Traceback (most recent call last):
07/29 05:11:42.122 INFO |run_chromeos_tests:0052|     File "/usr/local/telemetry/src/third_party/catapult/telemetry/telemetry/testing/browser_test_case.py", line 41, in WrappedMethod
07/29 05:11:42.123 INFO |run_chromeos_tests:0052|       method(self)
07/29 05:11:42.123 INFO |run_chromeos_tests:0052|     File "/usr/local/telemetry/src/tools/perf/core/about_tracing_integration_test.py", line 34, in testBasicTraceRecording
07/29 05:11:42.124 INFO |run_chromeos_tests:0052|       action_runner.WaitForElement(selector='div[title~="Browser"]')
07/29 05:11:42.125 INFO |run_chromeos_tests:0052|     File "/usr/local/telemetry/src/third_party/catapult/telemetry/telemetry/internal/actions/action_runner.py", line 206, in WaitForElement
07/29 05:11:42.125 INFO |run_chromeos_tests:0052|       timeout_in_seconds=timeout_in_seconds))
07/29 05:11:42.126 INFO |run_chromeos_tests:0052|     File "/usr/local/telemetry/src/third_party/catapult/telemetry/telemetry/internal/actions/action_runner.py", line 45, in _RunAction
07/29 05:11:42.127 INFO |run_chromeos_tests:0052|       action.RunAction(self._tab)
07/29 05:11:42.127 INFO |run_chromeos_tests:0052|     File "/usr/local/telemetry/src/third_party/catapult/telemetry/telemetry/internal/actions/wait.py", line 22, in RunAction
07/29 05:11:42.128 INFO |run_chromeos_tests:0052|       wait=True, timeout_in_seconds=self.timeout_in_seconds)
07/29 05:11:42.129 INFO |run_chromeos_tests:0052|     File "/usr/local/telemetry/src/third_party/catapult/telemetry/telemetry/internal/actions/page_action.py", line 113, in EvaluateCallbackWithElement
07/29 05:11:42.129 INFO |run_chromeos_tests:0052|       tab.WaitForJavaScriptExpression(code, timeout_in_seconds)
07/29 05:11:42.130 INFO |run_chromeos_tests:0052|     File "/usr/local/telemetry/src/third_party/catapult/telemetry/telemetry/internal/browser/web_contents.py", line 136, in WaitForJavaScriptExpression
07/29 05:11:42.131 INFO |run_chromeos_tests:0052|       e.message + '\n' + debug_message)
07/29 05:11:42.131 INFO |run_chromeos_tests:0052|   TimeoutException: Timed out while waiting 60s for IsJavaScriptExpressionTrue.
07/29 05:11:42.132 INFO |run_chromeos_tests:0052|   Console output:
07/29 05:11:42.133 INFO |run_chromeos_tests:0052|   (log) chrome://tracing/tracing.js:1471: SyntaxError: Unexpected end of JSON input
07/29 05:11:42.133 INFO |run_chromeos_tests:0052|   (log) chrome://tracing/tracing.js:2069: Error: Could not find an importer for the provided eventData.
07/29 05:11:42.134 INFO |run_chromeos_tests:0052|       at Import.createImports (chrome://tracing/tracing.js:1472:64)
07/29 05:11:42.135 INFO |run_chromeos_tests:0052|       at Task.run (chrome://tracing/tracing.js:2057:13)
07/29 05:11:42.135 INFO |run_chromeos_tests:0052|       at runAnother (chrome://tracing/tracing.js:2069:136)
07/29 05:11:42.136 INFO |run_chromeos_tests:0052|       at runTask (chrome://tracing/tracing.js:2032:57)
07/29 05:11:42.137 INFO |run_chromeos_tests:0052|       at processIdleWork (chrome://tracing/tracing.js:2038:116)
07/29 05:11:42.137 INFO |run_chromeos_tests:0052|       at window.requestIdleCallback.timeout (chrome://tracing/tracing.js:2026:81)
07/29 05:11:42.138 INFO |run_chromeos_tests:0052|   



First failing build:
https://uberchromegw.corp.google.com/i/chromiumos.chromium/builders/amd64-generic-telemetry/builds/9435

The only catapult change here is this, which seems an unlikely culprit:
https://codereview.chromium.org/2185933002