Add SpdyString alias for std::string in net/spdy.

net/spdy/header_coalescer.cc

 // Copyright (c) 2016 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/spdy/header_coalescer.h"
 
 #include <utility>
 
 #include "base/strings/string_util.h"
 #include "net/http/http_util.h"
 #include "net/spdy/platform/api/spdy_estimate_memory_usage.h"
+#include "net/spdy/platform/api/spdy_string.h"
 
 namespace net {
 
 const size_t kMaxHeaderListSize = 256 * 1024;
 
 void HeaderCoalescer::OnHeader(SpdyStringPiece key, SpdyStringPiece value) {
   if (error_seen_) {
     return;
   }
 
@@ skipping 32 matching lines @@
     error_seen_ = true;
     return;
   }
 
   auto iter = headers_.find(key);
   if (iter == headers_.end()) {
     headers_[key] = value;
   } else {
     // This header had multiple values, so it must be reconstructed.
     SpdyStringPiece v = iter->second;
-    std::string s(v.data(), v.length());
+    SpdyString s(v.data(), v.length());
     if (key == "cookie") {
       // Obeys section 8.1.2.5 in RFC 7540 for cookie reconstruction.
       s.append("; ");
     } else {
       SpdyStringPiece("\0", 1).AppendToString(&s);
     }
     value.AppendToString(&s);
     headers_[key] = s;
   }
 }
 
 SpdyHeaderBlock HeaderCoalescer::release_headers() {
   DCHECK(headers_valid_);
   headers_valid_ = false;
   return std::move(headers_);
 }
 
 size_t HeaderCoalescer::EstimateMemoryUsage() const {
   return SpdyEstimateMemoryUsage(headers_);
 }
 
 }  // namespace net