cc: Add RandomAccessListContainer, which has more restricted API.

cc/base/list_container_helper.h

 // Copyright 2015 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_HELPER_H_
 #define CC_BASE_LIST_CONTAINER_HELPER_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "cc/base/cc_export.h"
 
 namespace cc {
 
 // Helper class for ListContainer non-templated logic. All methods are private,
 // and only exposed to friend classes.
 // For usage, see comments in ListContainer (list_container.h).
 class CC_EXPORT ListContainerHelper final {
  private:
   template <typename T>
   friend class ListContainer;
 
+  template <typename T>
+  friend class RandomAccessListContainer;
+
   explicit ListContainerHelper(size_t max_size_for_derived_class);
   ListContainerHelper(size_t max_size_for_derived_class,
                       size_t num_of_elements_to_reserve_for);
   ~ListContainerHelper();
 
   // This class deals only with char* and void*. It does allocation and passing
   // out raw pointers, as well as memory deallocation when being destroyed.
   class CharAllocator;
 
   // This class points to a certain position inside memory of
@@ skipping 135 matching lines @@
   void* Allocate(size_t size_of_actual_element_in_bytes);
 
   scoped_ptr<CharAllocator> data_;
 
   DISALLOW_COPY_AND_ASSIGN(ListContainerHelper);
 };
 
 }  // namespace cc
 
 #endif  // CC_BASE_LIST_CONTAINER_HELPER_H_