tree 4fbb17bcef8921c21fffbedf66e1cbb99840cb37
parent c1cab06be6b47a0f96c7dff58802680b2b583b88
author renjietang <renjietang@google.com> 1560980102 -0700
committer Copybara-Service <copybara-worker@google.com> 1561039423 -0700

Make writing Prioritized Element ID and Element Dependency ID optional when handling priority.

These fields are specified to be absent when priority type or dependency type is ROOT_OF_TREE.

On the decoding side, the absent fields will be parsed as 0 for default value. Those fields won't be used when later the frame is processed.

gfe-relnote: v99 only, not flag protected.
PiperOrigin-RevId: 254072432
Change-Id: I336e06b39d89ff01507e54818dafa67923e96e4c