Blink's wtf/Assertions.h defines DCHECK_AT(), a variant which allows the file and line-number parameters to be supplied explicitly.  This is used to have DCHECKs on unexpected exception throwing call out the code that threw the exception, rather than the exception code itself.

We should fold DCHECK_AT into base/logging.h and have DCHECK() become just shorthand for it, rather than maintaining parallel and (over time) subtley different implementations.