chrome: Add out-of-line copy ctors for complex classes.

chrome/browser/performance_monitor/process_metrics_history.h

 // Copyright 2013 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_PROCESS_METRICS_HISTORY_H_
 #define CHROME_BROWSER_PERFORMANCE_MONITOR_PROCESS_METRICS_HISTORY_H_
 
 #include "base/macros.h"
 #include "base/memory/linked_ptr.h"
 #include "base/process/process_handle.h"
@@ skipping 20 matching lines @@
 
   ProcessMetricsMetadata()
       : handle(base::kNullProcessHandle),
         process_type(content::PROCESS_TYPE_UNKNOWN),
         process_subtype(kProcessSubtypeUnknown) {}
 };
 
 class ProcessMetricsHistory {
  public:
   ProcessMetricsHistory();
+  ProcessMetricsHistory(const ProcessMetricsHistory& other);
   ~ProcessMetricsHistory();
 
   // Configure this to monitor a specific process.
   void Initialize(const ProcessMetricsMetadata& process_data,
                   int initial_update_sequence);
 
   // Gather metrics for the process and accumulate with past data.
   void SampleMetrics();
 
   // Triggers any UMA histograms or background traces if cpu_usage is excessive.
@@ skipping 17 matching lines @@
   double cpu_usage_;
 
   content::BackgroundTracingManager::TriggerHandle trace_trigger_handle_;
 
   DISALLOW_ASSIGN(ProcessMetricsHistory);
 };
 
 }  // namespace performance_monitor
 
 #endif  // CHROME_BROWSER_PERFORMANCE_MONITOR_PROCESS_METRICS_HISTORY_H_