Implement RenderPassId StructTrait

cc/ipc/render_pass_id_struct_traits.h

Index: cc/ipc/render_pass_id_struct_traits.h
diff --git a/cc/ipc/render_pass_id_struct_traits.h b/cc/ipc/render_pass_id_struct_traits.h
new file mode 100644
index 0000000000000000000000000000000000000000..3601a921a1e6e7285b07db249b81c396e7661fb8
--- /dev/null
+++ b/cc/ipc/render_pass_id_struct_traits.h
@@ -0,0 +1,29 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.

[danakj, 2016/05/31 21:34:24]

How come this header file isn't part of any build targets?

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CC_IPC_RENDER_PASS_ID_STRUCT_TRAITS_H_
+#define CC_IPC_RENDER_PASS_ID_STRUCT_TRAITS_H_
+
+#include "cc/ipc/render_pass_id.mojom.h"
+#include "cc/quads/render_pass_id.h"
+
+namespace mojo {
+
+template <>
+struct StructTraits<cc::mojom::RenderPassId, cc::RenderPassId> {
+  static int layer_id(const cc::RenderPassId& id) { return id.layer_id; }
+
+  static uint32_t index(const cc::RenderPassId& id) { return id.index; }
+
+  static bool Read(cc::mojom::RenderPassIdDataView data,
+                   cc::RenderPassId* out) {
+    out->layer_id = data.layer_id();
+    out->index = data.index();
+    return true;
+  }
+};
+
+}  // namespace mojo
+
+#endif  // CC_IPC_RENDER_PASS_ID_STRUCT_TRAITS_H_