Add gpu::BufferBacking::shared_memory_handle()

gpu/command_buffer/common/buffer_unittest.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 "gpu/command_buffer/common/buffer.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace gpu {
+
+TEST(Buffer, SharedMemoryHandle) {
+  const size_t kSize = 1024;
+  std::unique_ptr<base::SharedMemory> shared_memory(new base::SharedMemory);
+  shared_memory->CreateAndMapAnonymous(kSize);
+  auto shared_memory_guid = shared_memory->handle().GetGUID();
+  scoped_refptr<Buffer> buffer =
+      MakeBufferFromSharedMemory(std::move(shared_memory), kSize);
+  EXPECT_EQ(buffer->backing()->shared_memory_handle().GetGUID(),
+            shared_memory_guid);
+}
+
+}  // namespace gpu