Virtual destructors should have virtual keyword.

chrome/renderer/renderer_histogram_snapshots.h

 // Copyright (c) 2010 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_RENDERER_RENDERER_HISTOGRAM_SNAPSHOTS_H_
 #define CHROME_RENDERER_RENDERER_HISTOGRAM_SNAPSHOTS_H_
 #pragma once
 
 #include <map>
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/metrics/histogram.h"
 #include "base/process.h"
 #include "base/task.h"
 #include "chrome/common/metrics_helpers.h"
 #include "content/renderer/render_process_observer.h"
 
 class RendererHistogramSnapshots : public HistogramSender,
                                    public RenderProcessObserver {
  public:
   RendererHistogramSnapshots();
-  ~RendererHistogramSnapshots();
+  virtual ~RendererHistogramSnapshots();
 
   // Send the histogram data.
   void SendHistograms(int sequence_number);
 
  private:
   // RenderProcessObserver implementation.
   virtual bool OnControlMessageReceived(const IPC::Message& message);
 
   void OnGetRendererHistograms(int sequence_number);
 
@@ skipping 16 matching lines @@
   virtual void UniqueInconsistencyDetected(int problem);
   virtual void SnapshotProblemResolved(int amount);
 
   // Collection of histograms to send to the browser.
   HistogramPickledList pickled_histograms_;
 
   DISALLOW_COPY_AND_ASSIGN(RendererHistogramSnapshots);
 };
 
 #endif  // CHROME_RENDERER_RENDERER_HISTOGRAM_SNAPSHOTS_H_