Only send Header Acknowledgement from QpackDecoder if required insert count is not zero.

As prescribed by
https://quicwg.org/base-drafts/draft-ietf-quic-qpack.html#header-acknowledgement.

I have a draft dynamic table encoder CL and a draft round trip fuzzer CL
relaying encoder stream data and decoder stream data between the encoder and
decoder, and I noticed this bug when patching these two CLs together.

gfe-relnote: n/a, change to QUIC v99-only code.  Protected by existing disabled gfe2_reloadable_flag_quic_enable_version_99.
PiperOrigin-RevId: 263253859
Change-Id: I766e4746d7ce88c6214f46d9cb5e35877b1f93e8

quic/core/qpack/qpack_decoded_headers_accumulator_test.cc

diff --git a/quic/core/qpack/qpack_decoded_headers_accumulator_test.cc b/quic/core/qpack/qpack_decoded_headers_accumulator_test.cc
index 3f7ae25..2a0a222 100644
--- a/quic/core/qpack/qpack_decoded_headers_accumulator_test.cc
+++ b/quic/core/qpack/qpack_decoded_headers_accumulator_test.cc
@@ -81,9 +81,6 @@
 }
 
 TEST_F(QpackDecodedHeadersAccumulatorTest, EmptyHeaderList) {
-  EXPECT_CALL(decoder_stream_sender_delegate_,
-              WriteStreamData(Eq(kHeaderAcknowledgement)));
-
   EXPECT_TRUE(accumulator_.Decode(QuicTextUtils::HexDecode("0000")));
   EXPECT_EQ(Status::kSuccess, accumulator_.EndHeaderBlock());
 
@@ -105,9 +102,6 @@
 }
 
 TEST_F(QpackDecodedHeadersAccumulatorTest, Success) {
-  EXPECT_CALL(decoder_stream_sender_delegate_,
-              WriteStreamData(Eq(kHeaderAcknowledgement)));
-
   std::string encoded_data(QuicTextUtils::HexDecode("000023666f6f03626172"));
   EXPECT_TRUE(accumulator_.Decode(encoded_data));
   EXPECT_EQ(Status::kSuccess, accumulator_.EndHeaderBlock());
@@ -121,9 +115,6 @@
 }
 
 TEST_F(QpackDecodedHeadersAccumulatorTest, ExceedingLimit) {
-  EXPECT_CALL(decoder_stream_sender_delegate_,
-              WriteStreamData(Eq(kHeaderAcknowledgement)));
-
   // Total length of header list exceeds kMaxHeaderListSize.
   EXPECT_TRUE(accumulator_.Decode(QuicTextUtils::HexDecode(
       "0000"                                      // header block prefix

quic/core/qpack/qpack_decoder_test.cc

diff --git a/quic/core/qpack/qpack_decoder_test.cc b/quic/core/qpack/qpack_decoder_test.cc
index 5190975..506d60c 100644
--- a/quic/core/qpack/qpack_decoder_test.cc
+++ b/quic/core/qpack/qpack_decoder_test.cc
@@ -104,8 +104,6 @@
 
 TEST_P(QpackDecoderTest, EmptyHeaderBlock) {
   EXPECT_CALL(handler_, OnDecodingCompleted());
-  EXPECT_CALL(decoder_stream_sender_delegate_,
-              WriteStreamData(Eq(kHeaderAcknowledgement)));
 
   DecodeHeaderBlock(QuicTextUtils::HexDecode("0000"));
 }
@@ -113,8 +111,6 @@
 TEST_P(QpackDecoderTest, LiteralEntryEmptyName) {
   EXPECT_CALL(handler_, OnHeaderDecoded(Eq(""), Eq("foo")));
   EXPECT_CALL(handler_, OnDecodingCompleted());
-  EXPECT_CALL(decoder_stream_sender_delegate_,
-              WriteStreamData(Eq(kHeaderAcknowledgement)));
 
   DecodeHeaderBlock(QuicTextUtils::HexDecode("00002003666f6f"));
 }
@@ -122,8 +118,6 @@
 TEST_P(QpackDecoderTest, LiteralEntryEmptyValue) {
   EXPECT_CALL(handler_, OnHeaderDecoded(Eq("foo"), Eq("")));
   EXPECT_CALL(handler_, OnDecodingCompleted());
-  EXPECT_CALL(decoder_stream_sender_delegate_,
-              WriteStreamData(Eq(kHeaderAcknowledgement)));
 
   DecodeHeaderBlock(QuicTextUtils::HexDecode("000023666f6f00"));
 }
@@ -131,8 +125,6 @@
 TEST_P(QpackDecoderTest, LiteralEntryEmptyNameAndValue) {
   EXPECT_CALL(handler_, OnHeaderDecoded(Eq(""), Eq("")));
   EXPECT_CALL(handler_, OnDecodingCompleted());
-  EXPECT_CALL(decoder_stream_sender_delegate_,
-              WriteStreamData(Eq(kHeaderAcknowledgement)));
 
   DecodeHeaderBlock(QuicTextUtils::HexDecode("00002000"));
 }
@@ -140,8 +132,6 @@
 TEST_P(QpackDecoderTest, SimpleLiteralEntry) {
   EXPECT_CALL(handler_, OnHeaderDecoded(Eq("foo"), Eq("bar")));
   EXPECT_CALL(handler_, OnDecodingCompleted());
-  EXPECT_CALL(decoder_stream_sender_delegate_,
-              WriteStreamData(Eq(kHeaderAcknowledgement)));
 
   DecodeHeaderBlock(QuicTextUtils::HexDecode("000023666f6f03626172"));
 }
@@ -151,8 +141,6 @@
   std::string str(127, 'a');
   EXPECT_CALL(handler_, OnHeaderDecoded(Eq("foobaar"), QuicStringPiece(str)));
   EXPECT_CALL(handler_, OnDecodingCompleted());
-  EXPECT_CALL(decoder_stream_sender_delegate_,
-              WriteStreamData(Eq(kHeaderAcknowledgement)));
 
   DecodeHeaderBlock(QuicTextUtils::HexDecode(
       "0000"                // prefix
@@ -210,8 +198,6 @@
 TEST_P(QpackDecoderTest, HuffmanSimple) {
   EXPECT_CALL(handler_, OnHeaderDecoded(Eq("custom-key"), Eq("custom-value")));
   EXPECT_CALL(handler_, OnDecodingCompleted());
-  EXPECT_CALL(decoder_stream_sender_delegate_,
-              WriteStreamData(Eq(kHeaderAcknowledgement)));
 
   DecodeHeaderBlock(
       QuicTextUtils::HexDecode("00002f0125a849e95ba97d7f8925a849e95bb8e8b4bf"));
@@ -221,8 +207,6 @@
   EXPECT_CALL(handler_, OnHeaderDecoded(Eq("custom-key"), Eq("custom-value")))
       .Times(4);
   EXPECT_CALL(handler_, OnDecodingCompleted());
-  EXPECT_CALL(decoder_stream_sender_delegate_,
-              WriteStreamData(Eq(kHeaderAcknowledgement)));
 
   DecodeHeaderBlock(QuicTextUtils::HexDecode(
       "0000"                        // Prefix.
@@ -295,8 +279,6 @@
   EXPECT_CALL(handler_, OnHeaderDecoded(Eq("location"), Eq("foo")));
 
   EXPECT_CALL(handler_, OnDecodingCompleted());
-  EXPECT_CALL(decoder_stream_sender_delegate_,
-              WriteStreamData(Eq(kHeaderAcknowledgement)));
 
   DecodeHeaderBlock(QuicTextUtils::HexDecode(
       "0000d1dfccd45f108621e9aec2a11f5c8294e75f000554524143455f1000"));

quic/core/qpack/qpack_progressive_decoder.cc

diff --git a/quic/core/qpack/qpack_progressive_decoder.cc b/quic/core/qpack/qpack_progressive_decoder.cc
index e364edc..b3c374e 100644
--- a/quic/core/qpack/qpack_progressive_decoder.cc
+++ b/quic/core/qpack/qpack_progressive_decoder.cc
@@ -316,7 +316,10 @@
     return;
   }
 
-  decoder_stream_sender_->SendHeaderAcknowledgement(stream_id_);
+  if (required_insert_count_ > 0) {
+    decoder_stream_sender_->SendHeaderAcknowledgement(stream_id_);
+  }
+
   handler_->OnDecodingCompleted();
 }