Migrate StringPiece::CopyToString to string::assign.

net/tools/quic/quic_http_response_cache.h

 // Copyright (c) 2012 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.
 
 #ifndef NET_TOOLS_QUIC_QUIC_HTTP_RESPONSE_CACHE_H_
 #define NET_TOOLS_QUIC_QUIC_HTTP_RESPONSE_CACHE_H_
 
 #include <list>
 #include <map>
 #include <memory>
@@ skipping 47 matching lines @@
     const SpdyHeaderBlock& trailers() const { return trailers_; }
     const QuicStringPiece body() const { return QuicStringPiece(body_); }
 
     void set_response_type(SpecialResponseType response_type) {
       response_type_ = response_type;
     }
     void set_headers(SpdyHeaderBlock headers) { headers_ = std::move(headers); }
     void set_trailers(SpdyHeaderBlock trailers) {
       trailers_ = std::move(trailers);
     }
-    void set_body(QuicStringPiece body) { body.CopyToString(&body_); }
+    void set_body(QuicStringPiece body) {
+      body_.assign(body.data(), body.size());
+    }
 
    private:
     SpecialResponseType response_type_;
     SpdyHeaderBlock headers_;
     SpdyHeaderBlock trailers_;
     std::string body_;
 
     DISALLOW_COPY_AND_ASSIGN(Response);
   };
 
@@ skipping 135 matching lines @@
   // Protects against concurrent access from test threads setting responses, and
   // server threads accessing those responses.
   mutable QuicMutex response_mutex_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicHttpResponseCache);
 };
 
 }  // namespace net
 
 #endif  // NET_TOOLS_QUIC_QUIC_HTTP_RESPONSE_CACHE_H_