Repro steps:
1) Launch Chrome for the first time. First run experience should show
2) Tap "Accept & Continue" on the "Welcome to Chrome" page
3) Hit the back button. You should now be at the "Welcome to Chrome" page again
4) Tap "Accept & Continue" again

Expected:
No DCHECK() failure
Actual:
DCHECK() in RecordMetricsReportingDefaultState() fails