Leak reports collect information about the memory usage

chrome/browser/metrics/metrics_memory_details.h

 // Copyright 2015 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_METRICS_METRICS_MEMORY_DETAILS_H_
 #define CHROME_BROWSER_METRICS_METRICS_MEMORY_DETAILS_H_
 
 #include <map>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "build/build_config.h"
 #include "chrome/browser/memory_details.h"
 
 // MemoryGrowthTracker tracks latest metrics about record time and memory usage
 // at that time per process.
 class MemoryGrowthTracker {
  public:
   MemoryGrowthTracker();
   ~MemoryGrowthTracker();

[Alexei Svitkine (slow), 2016/10/11 16:47:48]

Make this virtual and mark it override in the subclass now that you're
inheriting from this.

[mwlodar, 2016/10/12 21:50:51]

Done.

 
   // If 30 minutes have passed since last UMA record, UpdateSample() computes
   // a difference between current memory usage |sample| of process |pid| and
   // stored memory usage at the time of last UMA record. Then, it updates the
   // stored memory usage to |sample|, stores the difference in |diff| and
   // returns true.
   // If no memory usage of |pid| has not been recorded so far or 30 minutes
   // have not passed since last record, it just returns false.
   // |sample| is memory usage in kB.
-  bool UpdateSample(base::ProcessId pid, int sample, int* diff);
+  virtual bool UpdateSample(base::ProcessId pid, int sample, int* diff);
 
  private:
   // Latest metrics about record time and memory usage at that time per process.
   // The second values of |memory_sizes_| are in kB.
   std::map<base::ProcessId, base::TimeTicks> times_;
   std::map<base::ProcessId, int> memory_sizes_;
 
   DISALLOW_COPY_AND_ASSIGN(MemoryGrowthTracker);
 };
 
@@ skipping 23 matching lines @@
 
   // A pointer to MemoryGrowthTracker which is contained in a longer-lived
   // owner of MetricsMemoryDetails, for example, ChromeMetricsServiceClient.
   // If it is null, nothing is tracked.
   MemoryGrowthTracker* memory_growth_tracker_;
 
   DISALLOW_COPY_AND_ASSIGN(MetricsMemoryDetails);
 };
 
 #endif  // CHROME_BROWSER_METRICS_METRICS_MEMORY_DETAILS_H_