Suppress pause-and-buffer behavior when the HTTP response won't satisfy future requests via cache.

net/http/http_response_headers.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // The rules for header parsing were borrowed from Firefox:
 // http://lxr.mozilla.org/seamonkey/source/netwerk/protocol/http/src/nsHttpResponseHead.cpp
 // The rules for parsing content-types were also borrowed from Firefox:
 // http://lxr.mozilla.org/mozilla/source/netwerk/base/src/nsURLHelper.cpp#834
 
 #include "net/http/http_response_headers.h"
@@ skipping 1142 matching lines @@
     keep_alive = LowerCaseEqualsASCII(connection_val, "keep-alive");
   } else {
     // HTTP/1.1 responses default to keep-alive
     keep_alive = !LowerCaseEqualsASCII(connection_val, "close");
   }
 
   return keep_alive;
 }
 
 bool HttpResponseHeaders::HasStrongValidators() const {
-  if (GetHttpVersion() < HttpVersion(1, 1))
-    return false;
-
-  std::string etag_value;
-  EnumerateHeader(NULL, "etag", &etag_value);
-  if (!etag_value.empty()) {
-    size_t slash = etag_value.find('/');
-    if (slash == std::string::npos || slash == 0)
-      return true;
-
-    std::string::const_iterator i = etag_value.begin();
-    std::string::const_iterator j = etag_value.begin() + slash;
-    HttpUtil::TrimLWS(&i, &j);
-    if (!LowerCaseEqualsASCII(i, j, "w"))
-      return true;
-  }
-
-  Time last_modified;
-  if (!GetLastModifiedValue(&last_modified))
-    return false;
-
-  Time date;
-  if (!GetDateValue(&date))
-    return false;
-
-  return ((date - last_modified).InSeconds() >= 60);
+  std::string etag_header;
+  EnumerateHeader(NULL, "etag", &etag_header);
+  std::string last_modified_header;
+  EnumerateHeader(NULL, "Last-Modified", &last_modified_header);
+  std::string date_header;
+  EnumerateHeader(NULL, "Date", &date_header);
+  return HttpUtil::HasStrongValidators(GetHttpVersion(),
+                                       etag_header,
+                                       last_modified_header,
+                                       date_header);
 }
 
 // From RFC 2616:
 // Content-Length = "Content-Length" ":" 1*DIGIT
 int64 HttpResponseHeaders::GetContentLength() const {
   void* iter = NULL;
   std::string content_length_val;
   if (!EnumerateHeader(&iter, "content-length", &content_length_val))
     return -1;
 
@@ skipping 123 matching lines @@
   return true;
 }
 
 bool HttpResponseHeaders::IsChunkEncoded() const {
   // Ignore spurious chunked responses from HTTP/1.0 servers and proxies.
   return GetHttpVersion() >= HttpVersion(1, 1) &&
       HasHeaderValue("Transfer-Encoding", "chunked");
 }
 
 }  // namespace net