PR_USEC_PER_SEC  1184 base/third_party/nspr/prtime.cc                       LL_I2L(usec_per_sec, PR_USEC_PER_SEC);
PR_USEC_PER_SEC    64 base/time/pr_time_unittest.cc   PRTime current_time64 = static_cast<PRTime>(current_time) * PR_USEC_PER_SEC;