Looking at the crash reports from Issue 681443 I found that roughly 30% of the crashes on Windows has a different stack trace, not obviously related to the background optimizations.

See https://crash.corp.google.com/browse?q=custom_data.ChromeCrashProto.ptype%3D%27renderer%27%20AND%20custom_data.ChromeCrashProto.magic_signature_1.name%3D%27media%3A%3ARendererImpl%3A%3AGetMediaTime%27%20AND%20product.name%3D%27Chrome%27%20OMIT%20RECORD%20IF%20SUM(custom_data.ChromeCrashProto.experiments.ids%3D%276c18ba9d-848e0891%27)%20!%3D%200&ignore_case=false&enable_rewrite=false&omit_field_name=custom_data.ChromeCrashProto.experiments.ids&omit_field_value=6c18ba9d-848e0891&omit_field_opt=%3D to filter out the experiment.

(sample report; https://crash.corp.google.com/browse?q=custom_data.ChromeCrashProto.ptype%3D%27renderer%27%20AND%20custom_data.ChromeCrashProto.magic_signature_1.name%3D%27media%3A%3ARendererImpl%3A%3AGetMediaTime%27%20AND%20product.name%3D%27Chrome%27%20OMIT%20RECORD%20IF%20SUM(custom_data.ChromeCrashProto.experiments.ids%3D%276c18ba9d-848e0891%27)%20!%3D%200&ignore_case=false&enable_rewrite=false&omit_field_name=custom_data.ChromeCrashProto.experiments.ids&omit_field_value=6c18ba9d-848e0891&omit_field_opt=%3D&stbtiq=&reportid=70fc324880000000&index=0)

The stack trace:
0x0fd96aad	(chrome_child.dll -renderer_impl.cc:310 )	media::RendererImpl::GetMediaTime()
0x0fd96a83	(chrome_child.dll -pipeline_impl.cc:440 )	media::PipelineImpl::RendererWrapper::GetMediaTime()
0x0fd969f1	(chrome_child.dll -pipeline_impl.cc:1076 )	media::PipelineImpl::GetMediaTime()
0x0fd96969	(chrome_child.dll -webmediaplayer_impl.cc:711 )	media::WebMediaPlayerImpl::currentTime()
0x0fd96929	(chrome_child.dll -htmlmediaelement.cpp:1908 )	blink::HTMLMediaElement::refreshCachedTime()
0x0fd968f2	(chrome_child.dll -htmlmediaelement.cpp:1942 )	blink::HTMLMediaElement::currentTime()