Return unique_ptrs from base::ProcessMetrics.

chrome/browser/performance_monitor/performance_monitor.h

 // 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.
 
 #ifndef CHROME_BROWSER_PERFORMANCE_MONITOR_PERFORMANCE_MONITOR_H_
 #define CHROME_BROWSER_PERFORMANCE_MONITOR_PERFORMANCE_MONITOR_H_
 
 #include <map>
 #include <memory>
 #include <vector>
 
+#include "base/lazy_instance.h"
 #include "base/macros.h"
 #include "base/process/process_handle.h"
 #include "base/timer/timer.h"
 #include "chrome/browser/performance_monitor/process_metrics_history.h"
 
-namespace base {
-template <typename Type>
-struct DefaultSingletonTraits;
-}  // namespace base
-
 namespace content {
 struct ChildProcessData;
 }
 
 namespace performance_monitor {
 
+class ProcessMetricsHistory;
+
 // PerformanceMonitor is a tool which periodically monitors performance metrics
 // for histogram logging and possibly taking action upon noticing serious
 // performance degradation.
 class PerformanceMonitor {
  public:
   // Returns the current PerformanceMonitor instance if one exists; otherwise
   // constructs a new PerformanceMonitor.
   static PerformanceMonitor* GetInstance();
 
   // Start the cycle of metrics gathering.
   void StartGatherCycle();
 
  private:
-  typedef std::map<base::ProcessHandle, ProcessMetricsHistory> MetricsMap;
+  friend struct base::DefaultLazyInstanceTraits<PerformanceMonitor>;
 
-  friend struct base::DefaultSingletonTraits<PerformanceMonitor>;
+  using MetricsMap =
+      std::map<base::ProcessHandle, std::unique_ptr<ProcessMetricsHistory>>;
 
   PerformanceMonitor();
-  virtual ~PerformanceMonitor();
+  ~PerformanceMonitor();
 
   // Perform any collections that are done on a timed basis.
   void DoTimedCollections();
 
   // Mark the given process as alive in the current update iteration.
   // This means adding an entry to the map of watched processes if it's not
   // already present.
   void MarkProcessAsAlive(const ProcessMetricsMetadata& process_data,
                           int current_update_sequence);
   void MarkProcessesAsAliveOnUIThread(
@@ skipping 13 matching lines @@
 
   // The timer to signal PerformanceMonitor to perform its timed collections.
   base::OneShotTimer repeating_timer_;
 
   DISALLOW_COPY_AND_ASSIGN(PerformanceMonitor);
 };
 
 }  // namespace performance_monitor
 
 #endif  // CHROME_BROWSER_PERFORMANCE_MONITOR_PERFORMANCE_MONITOR_H_