Implement cc::SurfaceId StructTraits

cc/ipc/cc_struct_traits.h

Index: cc/ipc/cc_struct_traits.h
diff --git a/cc/ipc/cc_struct_traits.h b/cc/ipc/cc_struct_traits.h
new file mode 100644
index 0000000000000000000000000000000000000000..9a1b381e776daed02bc9a034a57330312f2950c9
--- /dev/null
+++ b/cc/ipc/cc_struct_traits.h
@@ -0,0 +1,31 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.

[Ken Rockot(use gerrit already), 2016/05/26 16:58:21]

This file needs to be included in some target's sources so dependencies can be
expressed properly. Using a component target does not make sense, so
//cc/ipc:ipc itself won't work. How about introducing (in //cc/ipc/BUILD.gn):

source_set("mojom_struct_traits") {
  sources = [
    "cc_struct_traits.h"
  ]

  public_deps = [
    # ...  whatever (anything the header depends on is a public dep)
  ]
}

[Fady Samuel, 2016/05/26 17:45:09]

This creates a circular dependency. As per offline conversation I'm ignoring
this request.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CC_IPC_CC_STRUCT_TRAITS_H_
+#define CC_IPC_CC_STRUCT_TRAITS_H_
+
+#include "cc/ipc/surface_id.mojom.h"
+#include "cc/surfaces/surface_id.h"
+
+namespace mojo {
+
+template <>
+struct StructTraits<cc::mojom::SurfaceId, cc::SurfaceId> {
+  static uint32_t id_namespace(const cc::SurfaceId& id) {
+    return id.id_namespace();
+  }
+
+  static uint32_t local_id(const cc::SurfaceId& id) { return id.local_id(); }
+
+  static uint64_t nonce(const cc::SurfaceId& id) { return id.nonce(); }
+
+  static bool Read(cc::mojom::SurfaceIdDataView data, cc::SurfaceId* out) {
+    *out = cc::SurfaceId(data.id_namespace(), data.local_id(), data.nonce());
+    return true;
+  }
+};
+
+}  // namespace mojo
+
+#endif  // CC_IPC_CC_STRUCT_TRAITS_H_