Use custom ListContainer to allocate DrawQuads

cc/quads/list_container.h

Index: cc/quads/list_container.h
diff --git a/cc/quads/list_container.h b/cc/quads/list_container.h
index 34a30aadd6e74c2403fce5d339d61b9f00c428e6..6c559f611e92379ecc4a151d5226bc849990f6a7 100644
--- a/cc/quads/list_container.h
+++ b/cc/quads/list_container.h
@@ -146,13 +146,21 @@ class CC_EXPORT ListContainer {
   const BaseElementType* front() const;
   const BaseElementType* back() const;
 
+  BaseElementType* ElementAt(size_t index);
+  const BaseElementType* ElementAt(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;