Added a unique command buffer ID for command buffers.

ppapi/shared_impl/command_buffer_id_pair.h

Index: ppapi/shared_impl/command_buffer_id_pair.h
diff --git a/ppapi/shared_impl/command_buffer_id_pair.h b/ppapi/shared_impl/command_buffer_id_pair.h
new file mode 100644
index 0000000000000000000000000000000000000000..6705e4df1ba15f2d4ea9c15efd075eb6d29f4ada
--- /dev/null
+++ b/ppapi/shared_impl/command_buffer_id_pair.h
@@ -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.
+
+#ifndef PPAPI_SHARED_IMPL_COMMAND_BUFFER_ID_PAIR_H_
+#define PPAPI_SHARED_IMPL_COMMAND_BUFFER_ID_PAIR_H_
+
+#include "gpu/command_buffer/common/constants.h"
+
+namespace ppapi {
+
+struct CommandBufferIDPair {
+  CommandBufferIDPair();
+  ~CommandBufferIDPair();
+
+  gpu::CommandBufferNamespace namespace_id;
+  uint64_t command_buffer_id;
+};
+
+} // namespace ppapi
+
+#endif // PPAPI_SHARED_IMPL_COMMAND_BUFFER_ID_PAIR_H_