Fix a bug that causes a DCHECK to sometimes get it for no good reason.

content/browser/appcache/appcache_request_handler.cc

 // Copyright (c) 2011 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 "content/browser/appcache/appcache_request_handler.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "content/browser/appcache/appcache.h"
@@ skipping 362 matching lines @@
     return;
   }
 
   if (should_reset_appcache_ && !manifest_url.is_empty()) {
     host_->service()->DeleteAppCacheGroup(
         manifest_url, net::CompletionCallback());
     DeliverNetworkResponse();
     return;
   }
 
-  if (IsResourceTypeFrame(resource_type_) && cache_id != kAppCacheNoCacheId) {
+  if (IsMainResourceType(resource_type_) && cache_id != kAppCacheNoCacheId) {
     // AppCacheHost loads and holds a reference to the main resource cache
     // for two reasons, firstly to preload the cache into the working set
     // in advance of subresource loads happening, secondly to prevent the
     // AppCache from falling out of the working set on frame navigations.
     host_->LoadMainResourceCache(cache_id);
     host_->set_preferred_manifest_url(manifest_url);
   }
 
   // 6.11.1 Navigating across documents, steps 10 and 14.
 
@@ skipping 107 matching lines @@
   if (!host_->associated_cache() ||
       !host_->associated_cache()->is_complete()) {
     DeliverNetworkResponse();
     return;
   }
 
   ContinueMaybeLoadSubResource();
 }
 
 }  // namespace content