API changes to Write path Session on down for FEC protection.

net/quic/quic_packet_generator.cc

Index: net/quic/quic_packet_generator.cc
diff --git a/net/quic/quic_packet_generator.cc b/net/quic/quic_packet_generator.cc
index 782fa355688e8984146b788d36315e3c2a8c9dc8..175f555f9843d247762bf731e711e62768300f5b 100644
--- a/net/quic/quic_packet_generator.cc
+++ b/net/quic/quic_packet_generator.cc
@@ -93,6 +93,7 @@ QuicConsumedData QuicPacketGenerator::ConsumeData(QuicStreamId id,
                                                   const IOVector& data_to_write,
                                                   QuicStreamOffset offset,
                                                   bool fin,
+                                                  FecProtection fec_protection,
                                                   QuicAckNotifier* notifier) {
   IsHandshake handshake = id == kCryptoStreamId ? IS_HANDSHAKE : NOT_HANDSHAKE;
   SendQueuedFrames(false);
@@ -104,6 +105,10 @@ QuicConsumedData QuicPacketGenerator::ConsumeData(QuicStreamId id,
     SerializeAndSendPacket();
   }
 
+  if (fec_protection == MUST_FEC_PROTECT) {
+    MaybeStartFecProtection();
+  }
+
   IOVector data = data_to_write;
   size_t data_size = data.TotalBufferSize();
   while (delegate_->ShouldGeneratePacket(NOT_RETRANSMISSION,
@@ -140,6 +145,11 @@ QuicConsumedData QuicPacketGenerator::ConsumeData(QuicStreamId id,
       // We're done writing the data. Exit the loop.
       // We don't make this a precondition because we could have 0 bytes of data
       // if we're simply writing a fin.
+      if (fec_protection == MUST_FEC_PROTECT) {
+        // Turn off FEC protection when we're done writing protected data.
+        DVLOG(1) << "Turning FEC protection OFF";
+        should_fec_protect_ = false;
+      }
       break;
     }
   }
@@ -206,13 +216,6 @@ void QuicPacketGenerator::MaybeStartFecProtection() {
   DCHECK(packet_creator_->IsFecProtected());
 }
 
-void QuicPacketGenerator::MaybeStopFecProtection(bool force) {
-  DVLOG(1) << "Turning FEC protection OFF";
-  // FEC protection will stop after the next FEC packet is transmitted.
-  should_fec_protect_ = false;
-  MaybeSendFecPacketAndCloseGroup(force);
-}
-
 void QuicPacketGenerator::MaybeSendFecPacketAndCloseGroup(bool force) {
   if (!packet_creator_->IsFecProtected() ||
       packet_creator_->HasPendingFrames()) {