Update from chromium https://crrev.com/302282

base/win/enum_variant.h

 // Copyright (c) 2011 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 BASE_WIN_ENUM_VARIANT_H_
 #define BASE_WIN_ENUM_VARIANT_H_
 
 #include <unknwn.h>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 15 matching lines @@
   VARIANT* ItemAt(unsigned long index);
 
   // IUnknown.
   ULONG STDMETHODCALLTYPE AddRef() override;
   ULONG STDMETHODCALLTYPE Release() override;
   STDMETHODIMP QueryInterface(REFIID riid, void** ppv) override;
 
   // IEnumVARIANT.
   STDMETHODIMP Next(ULONG requested_count,
                     VARIANT* out_elements,
-                    ULONG* out_elements_received);
-  STDMETHODIMP Skip(ULONG skip_count);
-  STDMETHODIMP Reset();
-  STDMETHODIMP Clone(IEnumVARIANT** out_cloned_object);
+                    ULONG* out_elements_received) override;
+  STDMETHODIMP Skip(ULONG skip_count) override;
+  STDMETHODIMP Reset() override;
+  STDMETHODIMP Clone(IEnumVARIANT** out_cloned_object) override;
 
  private:
   ~EnumVariant();
 
   scoped_ptr<VARIANT[]> items_;
   unsigned long count_;
   unsigned long current_index_;
 };
 
 }  // namespace win
 }  // namespace base
 
 #endif  // BASE_WIN_ENUM_VARIANT_H_