Add GenericSharedMemoryId and use w/ GpuMemoryBuffer

base/memory/generic_shared_memory_id.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 BASE_MEMORY_GENERIC_SHARED_MEMORY_ID_H_
+#define BASE_MEMORY_GENERIC_SHARED_MEMORY_ID_H_
+
+#include "base/base_export.h"
+#include "base/trace_event/memory_allocator_dump.h"
+
+namespace base {
+
+// Defines an ID type which is used accross all types of shared memory
+// allocations. This includes other types (IOSurfaces, SharedBitmaps), not
+// just base::SharedMemory.
+using GenericSharedMemoryId = int;
+
+// Generates GUID which can be used to trace shared memory using its
+// GenericSharedMemoryId.
+BASE_EXPORT base::trace_event::MemoryAllocatorDumpGuid
+GetGenericSharedMemoryGUIDForTracing(
+    uint64_t tracing_process_id,
+    GenericSharedMemoryId generic_shared_memory_id);
+
+}  // namespace base
+
+#endif  // BASE_MEMORY_GENERIC_SHARED_MEMORY_ID_H_