Remove #pragma once. Just from base/ for now.

base/memory/scoped_vector.h

 // Copyright (c) 2012 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_MEMORY_SCOPED_VECTOR_H_
 #define BASE_MEMORY_SCOPED_VECTOR_H_
-#pragma once
 
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/move.h"
 #include "base/stl_util.h"
 
 // ScopedVector wraps a vector deleting the elements from its
 // destructor.
 template <class T>
@@ skipping 96 matching lines @@
   // Like |erase()|, but doesn't delete the elements in [first, last).
   iterator weak_erase(iterator first, iterator last) {
     return v.erase(first, last);
   }
 
  private:
   std::vector<T*> v;
 };
 
 #endif  // BASE_MEMORY_SCOPED_VECTOR_H_