Use quiche string libraries in third_party/quic/core

gfe-relnote: n/a, no functional change
PiperOrigin-RevId: 285401547
Change-Id: Ice6d421ff7058fe2d47aee426d7634b6d403ee3f
diff --git a/quic/core/quic_flow_controller_test.cc b/quic/core/quic_flow_controller_test.cc
index e9854e9..8f4cdf7 100644
--- a/quic/core/quic_flow_controller_test.cc
+++ b/quic/core/quic_flow_controller_test.cc
@@ -8,12 +8,12 @@
 #include <utility>
 
 #include "net/third_party/quiche/src/quic/platform/api/quic_expect_bug.h"
-#include "net/third_party/quiche/src/quic/platform/api/quic_str_cat.h"
 #include "net/third_party/quiche/src/quic/platform/api/quic_test.h"
 #include "net/third_party/quiche/src/quic/test_tools/quic_connection_peer.h"
 #include "net/third_party/quiche/src/quic/test_tools/quic_flow_controller_peer.h"
 #include "net/third_party/quiche/src/quic/test_tools/quic_sent_packet_manager_peer.h"
 #include "net/third_party/quiche/src/quic/test_tools/quic_test_utils.h"
+#include "net/third_party/quiche/src/common/platform/api/quiche_str_cat.h"
 
 using testing::_;
 using testing::Invoke;
@@ -91,9 +91,9 @@
   // Try to send more bytes, violating flow control.
   EXPECT_CALL(*connection_,
               CloseConnection(QUIC_FLOW_CONTROL_SENT_TOO_MUCH_DATA, _, _));
-  EXPECT_QUIC_BUG(
-      flow_controller_->AddBytesSent(send_window_ * 10),
-      QuicStrCat("Trying to send an extra ", send_window_ * 10, " bytes"));
+  EXPECT_QUIC_BUG(flow_controller_->AddBytesSent(send_window_ * 10),
+                  quiche::QuicheStrCat("Trying to send an extra ",
+                                       send_window_ * 10, " bytes"));
   EXPECT_TRUE(flow_controller_->IsBlocked());
   EXPECT_EQ(0u, flow_controller_->SendWindowSize());
 }