Add GenericSharedMemoryId and use w/ GpuMemoryBuffer

content/common/generic_shared_memory_tracing_id_generator.cc

Index: content/common/generic_shared_memory_tracing_id_generator.cc
diff --git a/content/common/generic_shared_memory_tracing_id_generator.cc b/content/common/generic_shared_memory_tracing_id_generator.cc
new file mode 100644
index 0000000000000000000000000000000000000000..37499efc9249701126a53e2e1c5ce0f6e7af2ede
--- /dev/null
+++ b/content/common/generic_shared_memory_tracing_id_generator.cc
@@ -0,0 +1,22 @@
+// 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.
+
+#include "content/common/generic_shared_memory_tracing_id_generator.h"
+
+#include "base/atomic_sequence_num.h"
+
+namespace content {
+namespace {
+
+// Global atomic to generate gpu memory buffer unique IDs.
+base::StaticAtomicSequenceNumber g_next_generic_shared_memory_tracing_id;
+
+}  // namespace
+
+gfx::GenericSharedMemoryTracingId GetNextGenericSharedMemoryTracingId() {
+  return gfx::GenericSharedMemoryTracingId(
+      g_next_generic_shared_memory_tracing_id.GetNext());
+}
+
+}  // namespace content