Add the "virtual" keyword on method overrides that are missing it.

base/file_descriptor_shuffle.h

 // Copyright (c) 2009 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_FILE_DESCRIPTOR_SHUFFLE_H_
 #define BASE_FILE_DESCRIPTOR_SHUFFLE_H_
 #pragma once
 
 // This code exists to perform the shuffling of file descriptors which is
 // commonly needed when forking subprocesses. The naive approve is very simple,
@@ skipping 28 matching lines @@
   // Delete an element of the domain.
   virtual void Close(int fd) = 0;
 
  protected:
   virtual ~InjectionDelegate() {}
 };
 
 // An implementation of the InjectionDelegate interface using the file
 // descriptor table of the current process as the domain.
 class FileDescriptorTableInjection : public InjectionDelegate {
-  bool Duplicate(int* result, int fd);
-  bool Move(int src, int dest);
-  void Close(int fd);
+  virtual bool Duplicate(int* result, int fd);
+  virtual bool Move(int src, int dest);
+  virtual void Close(int fd);
 };
 
 // A single arc of the directed graph which describes an injective multimapping.
 struct InjectionArc {
   InjectionArc(int in_source, int in_dest, bool in_close)
       : source(in_source),
         dest(in_dest),
         close(in_close) {
   }
 
@@ skipping 13 matching lines @@
 
 // This function will not call malloc but will mutate |map|
 static inline bool ShuffleFileDescriptors(InjectiveMultimap* map) {
   FileDescriptorTableInjection delegate;
   return PerformInjectiveMultimapDestructive(map, &delegate);
 }
 
 }  // namespace base
 
 #endif  // BASE_FILE_DESCRIPTOR_SHUFFLE_H_