Add a size parameter to SharedMemoryHandle.

base/memory/shared_memory_handle.cc

 // Copyright 2017 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.
 
 #include "base/memory/shared_memory_handle.h"
 
 namespace base {
 
 SharedMemoryHandle::SharedMemoryHandle(const SharedMemoryHandle& handle) =
     default;
 
 SharedMemoryHandle& SharedMemoryHandle::operator=(
     const SharedMemoryHandle& handle) = default;
 
 base::UnguessableToken SharedMemoryHandle::GetGUID() const {
   return guid_;
 }
 
+size_t SharedMemoryHandle::GetSize() const {
+  return size_;
+}
+
 }  // namespace base