Factor out StringAppendF into spdy/platform/.

net/spdy/spdy_alt_svc_wire_format.cc

Index: net/spdy/spdy_alt_svc_wire_format.cc
diff --git a/net/spdy/spdy_alt_svc_wire_format.cc b/net/spdy/spdy_alt_svc_wire_format.cc
index bc844571a0d87a000bbadc443d96dd27ba93b90f..9097b5be5486d5b8d2aa61ed348ffc12c6934712 100644
--- a/net/spdy/spdy_alt_svc_wire_format.cc
+++ b/net/spdy/spdy_alt_svc_wire_format.cc
@@ -10,7 +10,7 @@
 
 #include "base/logging.h"
 #include "base/strings/string_util.h"

[diannahu, 2017/03/29 15:42:57]

Can this be removed?

[Bence, 2017/03/29 16:56:18]

Unfortunately not: it is needed for base::IsHexDigit() and base:HexDigitToInt().

[xunjieli, 2017/03/29 17:43:48]

I am still concerned about this approach. Does having the two repos exactly in
sync justify this code churn? Here, we aren't able to get rid of the direct
dependency of base/strings/string_util.h because there are two more methods need
to be migrated. I am concerned that we might introduce subtle bugs this way and
might cause more headaches down the road.

A good enough approach that works for me is to have the merge script to do a
find-and-replace. 

I know QUIC team is doing the same. Is there a discussion thread somewhere?

-#include "base/strings/stringprintf.h"
+#include "net/spdy/platform/api/spdy_string_utils.h"
 
 namespace net {
 
@@ -240,9 +240,9 @@ std::string SpdyAltSvcWireFormat::SerializeHeaderFieldValue(
       }
       value.push_back(c);
     }
-    base::StringAppendF(&value, ":%d\"", altsvc.port);
+    SpdyStringAppendF(&value, ":%d\"", altsvc.port);
     if (altsvc.max_age != 86400) {
-      base::StringAppendF(&value, "; ma=%d", altsvc.max_age);
+      SpdyStringAppendF(&value, "; ma=%d", altsvc.max_age);
     }
     if (!altsvc.version.empty()) {
       value.append("; v=\"");
@@ -251,7 +251,7 @@ std::string SpdyAltSvcWireFormat::SerializeHeaderFieldValue(
         if (it != altsvc.version.begin()) {
           value.append(",");
         }
-        base::StringAppendF(&value, "%d", *it);
+        SpdyStringAppendF(&value, "%d", *it);
       }
       value.append("\"");
     }