Update from https://crrev.com/303153

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 bde65dc797b14791a1911494bb4b8a18852c2667..211e6340159bf856b3bf9cbb96ee2649c1b68d84 100644
--- a/net/http/http_util.h
+++ b/net/http/http_util.h
@@ -10,6 +10,7 @@
 
 #include "base/memory/ref_counted.h"
 #include "base/strings/string_tokenizer.h"
+#include "base/time/time.h"
 #include "net/base/net_export.h"
 #include "net/http/http_byte_range.h"
 #include "net/http/http_version.h"
@@ -66,6 +67,15 @@ class NET_EXPORT HttpUtil {
   static bool ParseRangeHeader(const std::string& range_specifier,
                                std::vector<HttpByteRange>* ranges);
 
+  // Parses a Retry-After header that is either an absolute date/time or a
+  // number of seconds in the future. Interprets absolute times as relative to
+  // |now|. If |retry_after_string| is successfully parsed and indicates a time
+  // that is not in the past, fills in |*retry_after| and returns true;
+  // otherwise, returns false.
+  static bool ParseRetryAfterHeader(const std::string& retry_after_string,
+                                    base::Time now,
+                                    base::TimeDelta* retry_after);
+
   // 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