Convert DCHECKs to CHECKs for histogram types
When a histogram is looked up by name, there is currently a DCHECK that
verifies the type of the stored histogram matches the expected type.
A mismatch represents a significant problem because the returned
HistogramBase is cast to a Histogram in ValidateRangeChecksum,
potentially causing a crash.
This CL converts the DCHECK to a CHECK to prevent the possibility of
type confusion in release builds.