Async revalidation only applies to GET methods.

net/http/http_cache_transaction.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.
 
 #include "net/http/http_cache_transaction.h"
 
 #include "build/build_config.h"  // For OS_POSIX
 
 #if defined(OS_POSIX)
 #include <unistd.h>
@@ skipping 2340 matching lines @@
 
   if (request_->method == "PUT" || request_->method == "DELETE")
     return VALIDATION_SYNCHRONOUS;
 
   ValidationType validation_required_by_headers =
       response_.headers->RequiresValidation(response_.request_time,
                                             response_.response_time,
                                             cache_->clock_->Now());
 
   if (validation_required_by_headers == VALIDATION_ASYNCHRONOUS) {
-    // Asynchronous revalidation is only supported for GET and HEAD methods.
-    if (request_->method != "GET" && request_->method != "HEAD")
+    // Asynchronous revalidation is only supported for GET methods.
+    if (request_->method != "GET")
       return VALIDATION_SYNCHRONOUS;
   }
 
   return validation_required_by_headers;
 }
 
 bool HttpCache::Transaction::ConditionalizeRequest() {
   DCHECK(response_.headers.get());
 
   if (request_->method == "PUT" || request_->method == "DELETE")
@@ skipping 576 matching lines @@
     default:
       NOTREACHED();
   }
 }
 
 void HttpCache::Transaction::OnIOComplete(int result) {
   DoLoop(result);
 }
 
 }  // namespace net