Standardize usage of virtual/override/final in chrome/browser/

chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.h

Index: chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.h
diff --git a/chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.h b/chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.h
index 04f3f0e1f3008fa24599288113abd9565c1a82c0..0e43b9b822ca720ac2892f4001c11133caa34f0c 100644
--- a/chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.h
+++ b/chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.h
@@ -19,12 +19,12 @@ void AddMetricsExtraParts(ChromeBrowserMainParts* main_parts);
 class ChromeBrowserMainExtraPartsMetrics : public ChromeBrowserMainExtraParts {
  public:
   ChromeBrowserMainExtraPartsMetrics();
-  virtual ~ChromeBrowserMainExtraPartsMetrics();
+  ~ChromeBrowserMainExtraPartsMetrics() override;
 
   // Overridden from ChromeBrowserMainExtraParts:
-  virtual void PreProfileInit() override;
-  virtual void PreBrowserStart() override;
-  virtual void PostBrowserStart() override;
+  void PreProfileInit() override;
+  void PreBrowserStart() override;
+  void PostBrowserStart() override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ChromeBrowserMainExtraPartsMetrics);