Add QuicStrCat.

net/quic/core/quic_flow_controller.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/core/quic_flow_controller.h"
 
 #include "base/strings/stringprintf.h"
 #include "net/quic/core/quic_bug_tracker.h"
 #include "net/quic/core/quic_connection.h"
 #include "net/quic/core/quic_flags.h"
@@ skipping 59 matching lines @@
 void QuicFlowController::AddBytesSent(QuicByteCount bytes_sent) {
   if (bytes_sent_ + bytes_sent > send_window_offset_) {
     QUIC_BUG << ENDPOINT << "Stream " << id_ << " Trying to send an extra "
              << bytes_sent << " bytes, when bytes_sent = " << bytes_sent_
              << ", and send_window_offset_ = " << send_window_offset_;
     bytes_sent_ = send_window_offset_;
 
     // This is an error on our side, close the connection as soon as possible.
     connection_->CloseConnection(
         QUIC_FLOW_CONTROL_SENT_TOO_MUCH_DATA,
-        base::StringPrintf(
-            "%llu bytes over send window offset",
-            static_cast<unsigned long long>(send_window_offset_ -
-                                            (bytes_sent_ + bytes_sent)))
-            .c_str(),
+        QuicStrCat(send_window_offset_ - (bytes_sent_ + bytes_sent),
+                   "bytes over send window offset"),
         ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET);
     return;
   }
 
   bytes_sent_ += bytes_sent;
   DVLOG(1) << ENDPOINT << "Stream " << id_ << " sent: " << bytes_sent_;
 }
 
 bool QuicFlowController::FlowControlViolation() {
   if (highest_received_byte_offset_ > receive_window_offset_) {
@@ skipping 152 matching lines @@
   if (receive_window_size_ != receive_window_offset_) {
     QUIC_BUG << "receive_window_size_:" << receive_window_size_
              << " != receive_window_offset:" << receive_window_offset_;
     return;
   }
   receive_window_size_ = size;
   receive_window_offset_ = size;
 }
 
 }  // namespace net