Standardize usage of virtual/override/final in content/

content/child/fileapi/webfilewriter_impl.h

Index: content/child/fileapi/webfilewriter_impl.h
diff --git a/content/child/fileapi/webfilewriter_impl.h b/content/child/fileapi/webfilewriter_impl.h
index 008a9843830b9b56928feba21380bd88162efa4a..8aefaf516988290a6448cc2a7f805e8cdbbe3728 100644
--- a/content/child/fileapi/webfilewriter_impl.h
+++ b/content/child/fileapi/webfilewriter_impl.h
@@ -31,10 +31,11 @@ class WebFileWriterImpl : public WebFileWriterBase,
 
  protected:
   // WebFileWriterBase overrides
-  virtual void DoTruncate(const GURL& path, int64 offset) override;
-  virtual void DoWrite(const GURL& path, const std::string& blob_id,
-                       int64 offset) override;
-  virtual void DoCancel() override;
+  void DoTruncate(const GURL& path, int64 offset) override;
+  void DoWrite(const GURL& path,
+               const std::string& blob_id,
+               int64 offset) override;
+  void DoCancel() override;
 
  private:
   class WriterBridge;