message: Explicitly set enum type values.
  Summary: As in title.
diff: @@ -415,8 +415,8 @@ constexpr TransportPartialReliabilitySetting kDefaultPartialReliability = false;
  constexpr uint64_t kMaxPacketNumber = (1ull << 62) - 1;
  enum class ZeroRttSourceTokenMatchingPolicy : uint8_t {
  - REJECT_IF_NO_EXACT_MATCH,
  - LIMIT_IF_NO_EXACT_MATCH,
  + REJECT_IF_NO_EXACT_MATCH = 0,
  + LIMIT_IF_NO_EXACT_MATCH = 1,
  // T33014230 Subnet matching
  // REJECT_IF_NO_SUBNECT_MATCH,
  // LIMIT_IF_NO_EXACT_MATCH
  