Use custom ListContainer to allocate DrawQuads

cc/quads/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_QUADS_LIST_CONTAINER_H_
 #define CC_QUADS_LIST_CONTAINER_H_
 
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "cc/base/cc_export.h"
@@ skipping 128 matching lines @@
   ConstIterator begin() const;
   ConstIterator end() const;
   Iterator begin();
   Iterator end();
 
   BaseElementType* front();
   BaseElementType* back();
   const BaseElementType* front() const;
   const BaseElementType* back() const;
 
+  BaseElementType* at(size_t index);

[danakj, 2014/09/24 20:17:25]

This is an O(1) thing on std::vector, which is where you're getting this name
from, but it's not O(1) here so I think it's misleading to copy the name. That's
why I suggested ElementAt()

[weiliangc, 2014/09/24 20:26:31]

Make sense. Done.

+  const BaseElementType* at(size_t index) const;
+
   // Take in derived element type and construct it at location generated by
   // Allocate().
   template <typename DerivedElementType>
   DerivedElementType* AllocateAndConstruct() {
-    DerivedElementType* result =
-        new (Allocate(sizeof(DerivedElementType))) DerivedElementType;
-    return result;
+    return new (Allocate(sizeof(DerivedElementType))) DerivedElementType;
+  }
+  // Take in derived element type and copy construct it at location generated by
+  // Allocate().
+  template <typename DerivedElementType>
+  DerivedElementType* AllocateAndCopyFrom(const DerivedElementType* source) {
+    return new (Allocate(sizeof(DerivedElementType)))
+        DerivedElementType(*source);
   }
 
   size_t size() const;
   bool empty() const;
   void clear();
 
   size_t AvailableSizeWithoutAnotherAllocationForTesting() const;
 
  private:
   // Hands out memory location for an element at the end of data structure.
   BaseElementType* Allocate(size_t size_of_actual_element_in_bytes);
 
   scoped_ptr<ListContainerCharAllocator> data_;
 
   DISALLOW_COPY_AND_ASSIGN(ListContainer);
 };
 
 #if !defined(COMPILER_MSVC)
 extern template class ListContainer<SharedQuadState>;
 extern template class ListContainer<DrawQuad>;
 #endif
 }  // namespace cc
 
 #endif  // CC_QUADS_LIST_CONTAINER_H_