Loading from the "most appropiate" appcache.

webkit/appcache/web_application_cache_host_impl.cc

Index: webkit/appcache/web_application_cache_host_impl.cc
===================================================================
--- webkit/appcache/web_application_cache_host_impl.cc	(revision 78411)
+++ webkit/appcache/web_application_cache_host_impl.cc	(working copy)
@@ -156,7 +156,7 @@
 }
 
 void WebApplicationCacheHostImpl::willStartMainResourceRequest(
-    WebURLRequest& request) {
+    WebURLRequest& request, const WebFrame* frame) {
   request.setAppCacheHostID(host_id_);
 
   original_main_resource_url_ = ClearUrlRef(request.url());
@@ -164,6 +164,15 @@
   std::string method = request.httpMethod().utf8();
   is_get_method_ = (method == kHttpGETMethod);
   DCHECK(method == StringToUpperASCII(method));
+
+  CHECK(frame);  // just to see if this holds true or not on try bots?
+
+  if (frame) {
+    if (WebApplicationCacheHostImpl* parent = FromFrame(frame->parent()))
+      backend_->SetSpawningHostId(host_id_, parent->host_id());
+    else if (WebApplicationCacheHostImpl* opener = FromFrame(frame->opener()))
+      backend_->SetSpawningHostId(host_id_, opener->host_id());
+  }
 }
 
 void WebApplicationCacheHostImpl::willStartSubResourceRequest(