Remove std::string histogram name from HistogramBase object.

base/metrics/sparse_histogram_unittest.cc

 // Copyright (c) 2012 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/sparse_histogram.h"
 
 #include <memory>
 #include <string>
 
 #include "base/metrics/histogram_base.h"
@@ skipping 55 matching lines @@
     GlobalHistogramAllocator::CreateWithLocalMemory(
         kAllocatorMemorySize, 0, "SparseHistogramAllocatorTest");
     allocator_ = GlobalHistogramAllocator::Get()->memory_allocator();
   }
 
   void DestroyPersistentMemoryAllocator() {
     allocator_ = nullptr;
     GlobalHistogramAllocator::ReleaseForTesting();
   }
 
-  std::unique_ptr<SparseHistogram> NewSparseHistogram(const std::string& name) {
+  std::unique_ptr<SparseHistogram> NewSparseHistogram(const char* name) {
     return std::unique_ptr<SparseHistogram>(new SparseHistogram(name));
   }
 
   const bool use_persistent_histogram_allocator_;
 
   std::unique_ptr<StatisticsRecorder> statistics_recorder_;
   PersistentMemoryAllocator* allocator_ = nullptr;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SparseHistogramTest);
@@ skipping 87 matching lines @@
   UMA_HISTOGRAM_SPARSE_SLOWLY("Sparse", 200);
   UMA_HISTOGRAM_SPARSE_SLOWLY("Sparse", 100);
 
   StatisticsRecorder::Histograms histograms;
   StatisticsRecorder::GetHistograms(&histograms);
 
   ASSERT_EQ(1U, histograms.size());
   HistogramBase* sparse_histogram = histograms[0];
 
   EXPECT_EQ(SPARSE_HISTOGRAM, sparse_histogram->GetHistogramType());
-  EXPECT_EQ("Sparse", sparse_histogram->histogram_name());
+  EXPECT_EQ("Sparse", StringPiece(sparse_histogram->histogram_name()));
   EXPECT_EQ(
       HistogramBase::kUmaTargetedHistogramFlag |
           (use_persistent_histogram_allocator_ ? HistogramBase::kIsPersistent
                                                : 0),
       sparse_histogram->flags());
 
   std::unique_ptr<HistogramSamples> samples =
       sparse_histogram->SnapshotSamples();
   EXPECT_EQ(3, samples->TotalCount());
   EXPECT_EQ(2, samples->GetCount(100));
@@ skipping 190 matching lines @@
 }
 
 TEST_P(SparseHistogramTest, HistogramNameHash) {
   const char kName[] = "TestName";
   HistogramBase* histogram = SparseHistogram::FactoryGet(
       kName, HistogramBase::kUmaTargetedHistogramFlag);
   EXPECT_EQ(histogram->name_hash(), HashMetricName(kName));
 }
 
 }  // namespace base