Standardize usage of virtual/override/final in storage/

storage/browser/blob/blob_data_handle.h

Index: storage/browser/blob/blob_data_handle.h
diff --git a/storage/browser/blob/blob_data_handle.h b/storage/browser/blob/blob_data_handle.h
index 1120bdf54d2dbbf9ef482ab9b012565b174c5255..0b1d151c612e078ae6a91c3c052657a4f7d08e6a 100644
--- a/storage/browser/blob/blob_data_handle.h
+++ b/storage/browser/blob/blob_data_handle.h
@@ -29,7 +29,7 @@ class STORAGE_EXPORT BlobDataHandle
     : public base::SupportsUserData::Data {
  public:
   BlobDataHandle(const BlobDataHandle& other);  // May be copied on any thread.
-  virtual ~BlobDataHandle();  // Maybe be deleted on any thread.
+  ~BlobDataHandle() override;  // Maybe be deleted on any thread.
   BlobData* data() const;  // May only be accessed on the IO thread.
 
   std::string uuid() const;  // May be accessed on any thread.