Standardize usage of virtual/override/final in net/

net/url_request/url_request_about_job.h

Index: net/url_request/url_request_about_job.h
diff --git a/net/url_request/url_request_about_job.h b/net/url_request/url_request_about_job.h
index d4b4867ce41e368d0353a4fbad985d9d7aa6de35..36778b898648fe97350638e765510a5c64017a48 100644
--- a/net/url_request/url_request_about_job.h
+++ b/net/url_request/url_request_about_job.h
@@ -18,11 +18,11 @@ class NET_EXPORT URLRequestAboutJob : public URLRequestJob {
   URLRequestAboutJob(URLRequest* request, NetworkDelegate* network_delegate);
 
   // URLRequestJob:
-  virtual void Start() override;
-  virtual bool GetMimeType(std::string* mime_type) const override;
+  void Start() override;
+  bool GetMimeType(std::string* mime_type) const override;
 
  private:
-  virtual ~URLRequestAboutJob();
+  ~URLRequestAboutJob() override;
 
   void StartAsync();