Send `urgency` when sending `incremental`.

PiperOrigin-RevId: 504634170

quiche/quic/core/quic_stream_priority.cc

diff --git a/quiche/quic/core/quic_stream_priority.cc b/quiche/quic/core/quic_stream_priority.cc
index c378bfa..1d2e251 100644
--- a/quiche/quic/core/quic_stream_priority.cc
+++ b/quiche/quic/core/quic_stream_priority.cc
@@ -12,7 +12,9 @@
 std::string SerializePriorityFieldValue(QuicStreamPriority priority) {
   quiche::structured_headers::Dictionary dictionary;
 
-  if (priority.urgency != QuicStreamPriority::kDefaultUrgency &&
+  // TODO(b/266722347): Never send `urgency` if value equals default value.
+  if ((priority.urgency != QuicStreamPriority::kDefaultUrgency ||
+       priority.incremental != QuicStreamPriority::kDefaultIncremental) &&
       priority.urgency >= QuicStreamPriority::kMinimumUrgency &&
       priority.urgency <= QuicStreamPriority::kMaximumUrgency) {
     dictionary[QuicStreamPriority::kUrgencyKey] =

quiche/quic/core/quic_stream_priority_test.cc

diff --git a/quiche/quic/core/quic_stream_priority_test.cc b/quiche/quic/core/quic_stream_priority_test.cc
index f379a2a..88be74e 100644
--- a/quiche/quic/core/quic_stream_priority_test.cc
+++ b/quiche/quic/core/quic_stream_priority_test.cc
@@ -36,8 +36,9 @@
                     {/* urgency = */ 3, /* incremental = */ false}));
   EXPECT_EQ("u=5", SerializePriorityFieldValue(
                        {/* urgency = */ 5, /* incremental = */ false}));
-  EXPECT_EQ("i", SerializePriorityFieldValue(
-                     {/* urgency = */ 3, /* incremental = */ true}));
+  // TODO(b/266722347): Never send `urgency` if value equals default value.
+  EXPECT_EQ("u=3, i", SerializePriorityFieldValue(
+                          {/* urgency = */ 3, /* incremental = */ true}));
   EXPECT_EQ("u=0, i", SerializePriorityFieldValue(
                           {/* urgency = */ 0, /* incremental = */ true}));
   // Out-of-bound value is ignored.