Destroy PrerenderMessageFilter on the UI thread.

chrome/browser/prerender/prerender_message_filter.cc

Index: chrome/browser/prerender/prerender_message_filter.cc
diff --git a/chrome/browser/prerender/prerender_message_filter.cc b/chrome/browser/prerender/prerender_message_filter.cc
index d8d04de5f6f41956fedbef79c672b458d776b598..f69a1be4cedc806c4c5743f0ab9d1cd520b5350b 100644
--- a/chrome/browser/prerender/prerender_message_filter.cc
+++ b/chrome/browser/prerender/prerender_message_filter.cc
@@ -55,6 +55,7 @@ PrerenderMessageFilter::PrerenderMessageFilter(int render_process_id,
 }
 
 PrerenderMessageFilter::~PrerenderMessageFilter() {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
 }
 
 // static
@@ -91,6 +92,11 @@ void PrerenderMessageFilter::OnChannelClosing() {
       base::Bind(&PrerenderMessageFilter::OnChannelClosingInUIThread, this));
 }
 
+void PrerenderMessageFilter::OnDestruct() const {
+  // |shutdown_notifier_| needs to be destroyed on the UI thread.
+  BrowserThread::DeleteOnUIThread::Destruct(this);
+}
+
 void PrerenderMessageFilter::OnAddPrerender(
     int prerender_id,
     const PrerenderAttributes& attributes,