Make members of Singleton<T> private and only visible to the singleton type.

net/base/bandwidth_metrics.h

 // 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.
 
 #ifndef NET_BASE_BANDWIDTH_METRICS_H_
 #define NET_BASE_BANDWIDTH_METRICS_H_
 #pragma once
 
 #include <list>
 
@@ skipping 104 matching lines @@
   int64 bytes_since_last_start_;  // Bytes tracked during this "session".
   base::TimeTicks last_start_;    // Timestamp of the begin of this "session".
 };
 
 // A utility class for managing the lifecycle of a measured stream.
 // It is important that we not leave unclosed streams, and this class helps
 // ensure we always stop them.
 class ScopedBandwidthMetrics {
  public:
   ScopedBandwidthMetrics();
+  ~ScopedBandwidthMetrics();
 
-  ~ScopedBandwidthMetrics() {
-    if (started_)
-      metrics_->StopStream();
-  }
-
-  void StartStream() {
-    started_ = true;
-    metrics_->StartStream();
-  }
-
-  void StopStream() {
-    started_ = false;
-    metrics_->StopStream();
-  }
-
-  void RecordBytes(int bytes) { metrics_->RecordBytes(bytes); }
+  void StartStream();
+  void StopStream();
+  void RecordBytes(int bytes);
 
  private:
-  BandwidthMetrics* metrics_;
   bool started_;
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_BANDWIDTH_METRICS_H_
-