Use HttpRequestHeaders for extra_headers.

net/http/http_util.h

Index: net/http/http_util.h
diff --git a/net/http/http_util.h b/net/http/http_util.h
index c630cfe009103b9105c7c2f14310b0c02370ef75..4d4b200de5a1e10df10883c356ff91118fc5ad42 100644
--- a/net/http/http_util.h
+++ b/net/http/http_util.h
@@ -54,6 +54,11 @@ class HttpUtil {
   static bool ParseRanges(const std::string& headers,
                           std::vector<HttpByteRange>* ranges);
 
+  // Same thing as ParseRanges except the Range header is known and its value
+  // is directly passed in, rather than requiring searching through a string.
+  static bool ParseRangeHeader(const std::string& range_specifier,
+                               std::vector<HttpByteRange>* ranges);
+
   // Scans the '\r\n'-delimited headers for the given header name.  Returns
   // true if a match is found.  Input is assumed to be well-formed.
   // TODO(darin): kill this