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

base/metrics/persistent_sample_map_unittest.cc

 // Copyright (c) 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/metrics/persistent_sample_map.h"
 
 #include <memory>
 
 #include "base/memory/ptr_util.h"
 #include "base/metrics/persistent_histogram_allocator.h"
@@ skipping 229 matching lines @@
   HistogramSamples::Metadata meta;
   PersistentSampleMap samples(1, allocator.get(), &meta);
 
   std::unique_ptr<SampleCountIterator> it = samples.Iterator();
 
   EXPECT_TRUE(it->Done());
 
   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();
   EXPECT_FALSE(it->Done());
 }
 
 }  // namespace
 }  // namespace base