Add a new GetInstance() method for singleton classes under chrome/service and /net.

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 103 matching lines @@
   double data_sum_;               // The sum of all samples collected.
   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:
-  explicit ScopedBandwidthMetrics(BandwidthMetrics* metrics)
-      : metrics_(metrics), started_(false) {
-  }
+  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); }
 
  private:
   BandwidthMetrics* metrics_;
   bool started_;
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_BANDWIDTH_METRICS_H_