Implement StructTraits for various cc and gpu types

gpu/ipc/common/sync_token.mojom

Index: gpu/ipc/common/sync_token.mojom
diff --git a/gpu/ipc/common/sync_token.mojom b/gpu/ipc/common/sync_token.mojom
index 248ad315f864eae64301195c98995afd7e580f00..81bd5f01b78aaab7347d74c0c2798beda9849425 100644
--- a/gpu/ipc/common/sync_token.mojom
+++ b/gpu/ipc/common/sync_token.mojom
@@ -4,5 +4,23 @@
 
 module gpu.mojom;
 
-[Native]
-struct SyncToken;
+// See gpu/command_buffer/common/constants.h
+enum CommandBufferNamespace {
+  INVALID = -1,
+
+  GPU_IO,
+  IN_PROCESS,
+  MOJO,
+  MOJO_LOCAL,
+
+  NUM_COMMAND_BUFFER_NAMESPACES
+};
+
+// See gpu/command_buffer/common/sync_token.h
+struct SyncToken {
+  bool verified_flush;
+  CommandBufferNamespace namespace_id;
+  int32 extra_data_field;
+  uint64 command_buffer_id;
+  uint64 release_count;
+};