cc: Implement RemoveLast for DisplayItemList.

cc/base/sidecar_list_container.h

Index: cc/base/sidecar_list_container.h
diff --git a/cc/base/sidecar_list_container.h b/cc/base/sidecar_list_container.h
index 52deaf4b0a47f11b3eeabaa780bb1ee2bcded359..842795fad1b3a94d2ea644a89c6fbd99301e5e4e 100644
--- a/cc/base/sidecar_list_container.h
+++ b/cc/base/sidecar_list_container.h
@@ -29,6 +29,10 @@ class SidecarListContainer {
   using SidecarDestroyer = void (*)(void* sidecar);
   using Iterator = typename ListContainer<BaseElementType>::Iterator;
   using ConstIterator = typename ListContainer<BaseElementType>::ConstIterator;
+  using ReverseIterator =
+      typename ListContainer<BaseElementType>::ReverseIterator;
+  using ConstReverseIterator =
+      typename ListContainer<BaseElementType>::ConstReverseIterator;
 
   explicit SidecarListContainer(size_t max_size_for_derived_class,
                                 size_t max_size_for_sidecar,
@@ -60,6 +64,11 @@ class SidecarListContainer {
     list_.clear();
   }
 
+  void RemoveLast() {
+    destroyer_(GetSidecar(*list_.rbegin()));
+    list_.RemoveLast();
+  }
+
   // This permits a client to exchange a pointer to an element to a pointer to
   // its corresponding sidecar.
   void* GetSidecar(BaseElementType* element) {