Version: 55.0.2883.29 dev
OS: CrOS, Samus

What steps will reproduce the problem?
(1) go to chrome://tracing while system is very slow
(2) enable all options manually in the dialog and record and save the trace
(3) 

What is the expected output?
no errors

What do you see instead?

While importing:
Error: No clock sync markers exist pairing clock domain "LINUX_FTRACE_GLOBAL" with model clock domain "LINUX_CLOCK_MONOTONIC".
    at ClockSyncManager.getModelTimeTransformerRaw_ (chrome://tracing/tracing.js:2087:126)
    at ClockSyncManager.getModelTimeTransformer (chrome://tracing/tracing.js:2086:277)
    at FTraceImporter.importEvents (chrome://tracing/tracing.js:5567:425)
    at Import.runImportEventsOnOneImporter (chrome://tracing/tracing.js:1346:381)
    at Import.timedNamedFunction (chrome://tracing/tracing.js:573:310)
    at Task.run (chrome://tracing/tracing.js:2062:13)
    at runAnother (chrome://tracing/tracing.js:2074:136)
    at runTask (chrome://tracing/tracing.js:2037:57)
    at processIdleWork (chrome://tracing/tracing.js:2043:116)
    at window.requestIdleCallback.timeout (chrome://tracing/tracing.js:2031:81)

Feedback report available with id 21377850742