HttpRequestHeaders refactor.

net/http/http_network_transaction.h

Index: net/http/http_network_transaction.h
diff --git a/net/http/http_network_transaction.h b/net/http/http_network_transaction.h
index bf5327ad00b953eafdce9efffe15baa5a21cb624..24d2fb13f4613d5aeb9d458fa6bc12bc340feade 100644
--- a/net/http/http_network_transaction.h
+++ b/net/http/http_network_transaction.h
@@ -32,6 +32,7 @@ class ClientSocketFactory;
 class ClientSocketHandle;
 class SpdyStream;
 class HttpNetworkSession;
+class HttpRequestHeaders;
 class HttpStream;
 
 class HttpNetworkTransaction : public HttpTransaction {
@@ -217,9 +218,10 @@ class HttpNetworkTransaction : public HttpTransaction {
   // Returns true if we should try to add an Authorization header.
   bool ShouldApplyServerAuth() const;
 
-  // Builds either the proxy auth header, or the origin server auth header,
+  // Adds either the proxy auth header, or the origin server auth header,
   // as specified by |target|.
-  std::string BuildAuthorizationHeader(HttpAuth::Target target) const;
+  void AddAuthorizationHeader(
+      HttpAuth::Target target, HttpRequestHeaders* authorization_headers) const;
 
   // Returns a log message for all the response headers related to the auth
   // challenge.