Added HttpUtils::HasValidators and HttpResponse::HasValidators

net/http/http_util.cc

Index: net/http/http_util.cc
diff --git a/net/http/http_util.cc b/net/http/http_util.cc
index f1e5143e701a5334499dccc9a814ae4c96d2023b..c49a992706c19112eb7b4ba57cd5e362050c7ea1 100644
--- a/net/http/http_util.cc
+++ b/net/http/http_util.cc
@@ -736,9 +736,24 @@ bool HttpUtil::HasStrongValidators(HttpVersion version,
   if (!base::Time::FromString(date_header.c_str(), &date))
     return false;
 
+  // Last-Modified is implicitly weak unless it is at least 60 seconds before
+  // the Date value.
   return ((date - last_modified).InSeconds() >= 60);
 }
 
+bool HttpUtil::HasValidators(HttpVersion version,
+                             const std::string& etag_header,
+                             const std::string& last_modified_header) {
+  if (version < HttpVersion(1, 0))
+    return false;
+
+  base::Time last_modified;
+  if (base::Time::FromString(last_modified_header.c_str(), &last_modified))
+    return true;
+
+  return version >= HttpVersion(1, 1) && !etag_header.empty();
+}
+
 // Functions for histogram initialization.  The code 0 is put in the map to
 // track status codes that are invalid.
 // TODO(gavinp): Greatly prune the collected codes once we learn which