Only commit cookie changes in prerenders after a prerender is shown

content/browser/renderer_host/render_process_host_impl.cc

Index: content/browser/renderer_host/render_process_host_impl.cc
===================================================================
--- content/browser/renderer_host/render_process_host_impl.cc	(revision 269781)
+++ content/browser/renderer_host/render_process_host_impl.cc	(working copy)
@@ -1716,11 +1716,12 @@
 
   iterator iter(AllHostsIterator());
   while (!iter.IsAtEnd()) {
-    if (RenderProcessHostImpl::IsSuitableHost(
+    if (GetContentClient()->browser()->MayReuseHost(iter.GetCurrentValue()) &&
+        RenderProcessHostImpl::IsSuitableHost(
             iter.GetCurrentValue(),
-            browser_context, site_url))
+            browser_context, site_url)) {
       suitable_renderers.push_back(iter.GetCurrentValue());
-
+    }
     iter.Advance();
   }
 
@@ -1773,7 +1774,8 @@
   std::string site = SiteInstance::GetSiteForURL(browser_context, url)
       .possibly_invalid_spec();
   RenderProcessHost* host = map->FindProcess(site);
-  if (host && !IsSuitableHost(host, browser_context, url)) {
+  if (host && (!GetContentClient()->browser()->MayReuseHost(host) ||
+               !IsSuitableHost(host, browser_context, url))) {
     // The registered process does not have an appropriate set of bindings for
     // the url.  Remove it from the map so we can register a better one.
     RecordAction(