Add ListContainer::swap

cc/base/list_container.h

 // Copyright 2014 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 CC_BASE_LIST_CONTAINER_H_
 #define CC_BASE_LIST_CONTAINER_H_
 
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 270 matching lines @@
         DerivedElementType(*source);
   }
 
   // Construct a new element on top of an existing one.
   template <typename DerivedElementType>
   DerivedElementType* ReplaceExistingElement(Iterator at) {
     at->~BaseElementType();
     return new (*at) DerivedElementType();
   }
 
+  template <typename DerivedElementType>
+  void swap(ListContainer<DerivedElementType>& other) {
+    data_.swap(other.data_);
+  }
+
   // Appends a new item without copying. The original item will not be
   // destructed and will be replaced with a new DerivedElementType. The
   // DerivedElementType does not have to match the moved type as a full block
   // of memory will be moved (up to MaxSizeForDerivedClass()).
   template <typename DerivedElementType>
   void AppendByMoving(DerivedElementType* item) {
     size_t max_size_for_derived_class = MaxSizeForDerivedClass();
     void* new_item = Allocate(max_size_for_derived_class);
     memcpy(new_item, static_cast<void*>(item), max_size_for_derived_class);
     // Construct a new element in-place so it can be destructed safely.
@@ skipping 163 matching lines @@
         ListContainerBase::ConstReverseIterator base_iterator)
         : ListContainerBase::ConstReverseIterator(base_iterator) {}
     friend ConstReverseIterator ListContainer<BaseElementType>::crbegin() const;
     friend ConstReverseIterator ListContainer<BaseElementType>::crend() const;
   };
 };
 
 }  // namespace cc
 
 #endif  // CC_BASE_LIST_CONTAINER_H_