Change EXPECT/ASSERT_DCHECK_DEATH macro to not expose the |regex| parameter.

base/metrics/sample_map_unittest.cc

Index: base/metrics/sample_map_unittest.cc
diff --git a/base/metrics/sample_map_unittest.cc b/base/metrics/sample_map_unittest.cc
index 320ed9217b4274edb87dd9f079519e7a597ed33f..91a9dcf40f83d61506cf7c50b7246c48df9373ee 100644
--- a/base/metrics/sample_map_unittest.cc
+++ b/base/metrics/sample_map_unittest.cc
@@ -155,9 +155,9 @@ TEST(SampleMapIteratorDeathTest, IterateDoneTest) {
   HistogramBase::Sample min;
   HistogramBase::Sample max;
   HistogramBase::Count count;
-  EXPECT_DCHECK_DEATH(it->Get(&min, &max, &count), "");
+  EXPECT_DCHECK_DEATH(it->Get(&min, &max, &count));
 
-  EXPECT_DCHECK_DEATH(it->Next(), "");
+  EXPECT_DCHECK_DEATH(it->Next());
 
   samples.Accumulate(1, 100);
   it = samples.Iterator();