Use lock-free lazy initialization for static histogram references

net/socket_stream/socket_stream_metrics_unittest.cc

 // Copyright (c) 2009 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/basictypes.h"
 #include "base/metrics/histogram.h"
 #include "googleurl/src/gurl.h"
 #include "net/socket_stream/socket_stream_metrics.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/platform_test.h"
 
 using base::Histogram;
 using base::StatisticsRecorder;
 
 namespace net {
 
 TEST(SocketStreamMetricsTest, Initialize) {
   if (!StatisticsRecorder::IsActive()) {
     // Create the recorder if not yet started, as SocketStreamMetrics
     // relys on the StatisticsRecorder to be present. This is useful when
     // tests are run with --gtest_filter='SocketStreamMetricsTest*'.
     static StatisticsRecorder *recorder = NULL;
     recorder = new StatisticsRecorder;
   }
 }
 
 TEST(SocketStreamMetricsTest, ProtocolType) {
-  scoped_refptr<Histogram> histogram;
+  Histogram* histogram;
 
   // First we'll preserve the original values. We need to do this
   // as histograms can get affected by other tests. In particular,
   // SocketStreamTest and WebSocketTest can affect the histograms.
   Histogram::SampleSet original;
   if (StatisticsRecorder::FindHistogram(
           "Net.SocketStream.ProtocolType", &histogram)) {
     histogram->SnapshotSample(&original);
   }
 
@@ skipping 11 matching lines @@
   Histogram::SampleSet sample;
   histogram->SnapshotSample(&sample);
   original.Resize(*histogram);  // Ensure |original| size is same as |sample|.
   sample.Subtract(original); // Cancel the original values.
   EXPECT_EQ(1, sample.counts(SocketStreamMetrics::PROTOCOL_UNKNOWN));
   EXPECT_EQ(2, sample.counts(SocketStreamMetrics::PROTOCOL_WEBSOCKET));
   EXPECT_EQ(3, sample.counts(SocketStreamMetrics::PROTOCOL_WEBSOCKET_SECURE));
 }
 
 TEST(SocketStreamMetricsTest, ConnectionType) {
-  scoped_refptr<Histogram> histogram;
+  Histogram* histogram;
 
   // First we'll preserve the original values.
   Histogram::SampleSet original;
   if (StatisticsRecorder::FindHistogram(
           "Net.SocketStream.ConnectionType", &histogram)) {
     histogram->SnapshotSample(&original);
   }
 
   SocketStreamMetrics metrics(GURL("ws://www.example.com/"));
   for (int i = 0; i < 1; ++i)
@@ skipping 13 matching lines @@
   histogram->SnapshotSample(&sample);
   original.Resize(*histogram);
   sample.Subtract(original);
   EXPECT_EQ(1, sample.counts(SocketStreamMetrics::ALL_CONNECTIONS));
   EXPECT_EQ(2, sample.counts(SocketStreamMetrics::TUNNEL_CONNECTION));
   EXPECT_EQ(3, sample.counts(SocketStreamMetrics::SOCKS_CONNECTION));
   EXPECT_EQ(4, sample.counts(SocketStreamMetrics::SSL_CONNECTION));
 }
 
 TEST(SocketStreamMetricsTest, OtherNumbers) {
-  scoped_refptr<Histogram> histogram;
+  Histogram* histogram;
 
   // First we'll preserve the original values.
   int64 original_received_bytes = 0;
   int64 original_received_counts = 0;
   int64 original_sent_bytes = 0;
   int64 original_sent_counts = 0;
 
   Histogram::SampleSet original;
   if (StatisticsRecorder::FindHistogram(
           "Net.SocketStream.ReceivedBytes", &histogram)) {
@@ skipping 70 matching lines @@
 
   // SentCounts.
   ASSERT_TRUE(StatisticsRecorder::FindHistogram(
       "Net.SocketStream.SentCounts", &histogram));
   EXPECT_EQ(Histogram::kUmaTargetedHistogramFlag, histogram->flags());
   histogram->SnapshotSample(&sample);
   EXPECT_EQ(3, sample.sum() - original_sent_counts);  // 3 write requests.
 }
 
 }  // namespace net