Optimize chained string concatenation in SPDY code.

net/spdy/spdy_framer.cc

 // 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.
 
 #include "net/spdy/spdy_framer.h"
 
 #include "base/lazy_instance.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/stats_counters.h"
 #include "base/third_party/valgrind/memcheck.h"
@@ skipping 1321 matching lines @@
         }
       }
 
       WriteLengthZ(cookie_length, length_length, kZStandardData, z);
       for (size_t i = 0; i < cookie_values.size(); i++) {
         std::string cookie;
         // Since zlib will only back-reference complete cookies, a cookie that
         // is currently last (and so doesn't have a trailing semicolon) won't
         // match if it's later in a non-final position. The same is true of
         // the first cookie.
-        if (i == 0 && cookie_values.size() == 1) {
-          cookie = cookie_values[i].as_string();
-        } else if (i == 0) {
-          cookie = cookie_values[i].as_string() + ";";
-        } else if (i < cookie_values.size() - 1) {
-          cookie = " " + cookie_values[i].as_string() + ";";
-        } else {
-          cookie = " " + cookie_values[i].as_string();
-        }
+        if (i > 0)
+          cookie.append(" ");
+        cookie.append(cookie_values[i].as_string());
+        if (i < cookie_values.size() - 1)
+          cookie.append(";");

[mmenke, 2015/03/09 20:21:58]

Isn't this the same as:

if (i > 0)
  cookie.append("; ");
cookie.append(cookie_values[i].as_string());

         WriteZ(cookie, kZCookieData, z);
       }
     } else if (it->first == "accept" ||
                it->first == "accept-charset" ||
                it->first == "accept-encoding" ||
                it->first == "accept-language" ||
                it->first == "host" ||
                it->first == "version" ||
                it->first == "method" ||
                it->first == "scheme" ||
@@ skipping 1927 matching lines @@
   builder->Seek(compressed_size);
   builder->RewriteLength(*this);
 
   pre_compress_bytes.Add(uncompressed_len);
   post_compress_bytes.Add(compressed_size);
 
   compressed_frames.Increment();
 }
 
 }  // namespace net