Move CongestionControlTypeToString() into quic_types.h header It will be used for logging CC type in Chromium (<https://bugs.chromium.org/p/chromium/issues/detail?id=1291452>). PiperOrigin-RevId: 454664733

diff --git a/quiche/quic/core/congestion_control/send_algorithm_test.cc b/quiche/quic/core/congestion_control/send_algorithm_test.cc
index 21af4f1..76e61a3 100644
--- a/quiche/quic/core/congestion_control/send_algorithm_test.cc
+++ b/quiche/quic/core/congestion_control/send_algorithm_test.cc

@@ -102,22 +102,6 @@
 const QuicTime::Delta kTestLinkSmallRTTDelay =
     QuicTime::Delta::FromMilliseconds(10);
 
-const char* CongestionControlTypeToString(CongestionControlType cc_type) {
-  switch (cc_type) {
-    case kCubicBytes:
-      return "CUBIC_BYTES";
-    case kRenoBytes:
-      return "RENO_BYTES";
-    case kBBR:
-      return "BBR";
-    case kPCC:
-      return "PCC";
-    default:
-      QUIC_DLOG(FATAL) << "Unexpected CongestionControlType";
-      return nullptr;
-  }
-}
-
 struct TestParams {
   explicit TestParams(CongestionControlType congestion_control_type)
       : congestion_control_type(congestion_control_type) {}

diff --git a/quiche/quic/core/quic_types.cc b/quiche/quic/core/quic_types.cc
index 62760c9..6e74dd7 100644
--- a/quiche/quic/core/quic_types.cc
+++ b/quiche/quic/core/quic_types.cc

@@ -307,6 +307,24 @@
   return os;
 }
 
+std::string CongestionControlTypeToString(CongestionControlType cc_type) {
+  switch (cc_type) {
+    case kCubicBytes:
+      return "CUBIC_BYTES";
+    case kRenoBytes:
+      return "RENO_BYTES";
+    case kBBR:
+      return "BBR";
+    case kBBRv2:
+      return "BBRv2";
+    case kPCC:
+      return "PCC";
+    case kGoogCC:
+      return "GoogCC";
+  }
+  return absl::StrCat("Unknown(", static_cast<int>(cc_type), ")");
+}
+
 std::string EncryptionLevelToString(EncryptionLevel level) {
   switch (level) {
     RETURN_STRING_LITERAL(ENCRYPTION_INITIAL);

diff --git a/quiche/quic/core/quic_types.h b/quiche/quic/core/quic_types.h
index c79633c..b0992c8 100644
--- a/quiche/quic/core/quic_types.h
+++ b/quiche/quic/core/quic_types.h

@@ -452,6 +452,9 @@
   kBBRv2,
 };
 
+QUIC_EXPORT_PRIVATE std::string CongestionControlTypeToString(
+    CongestionControlType cc_type);
+
 // EncryptionLevel enumerates the stages of encryption that a QUIC connection
 // progresses through. When retransmitting a packet, the encryption level needs
 // to be specified so that it is retransmitted at a level which the peer can