Abandon prerenders upon render thread shutdown.

chrome/renderer/prerender/prerender_dispatcher.cc

Index: chrome/renderer/prerender/prerender_dispatcher.cc
diff --git a/chrome/renderer/prerender/prerender_dispatcher.cc b/chrome/renderer/prerender/prerender_dispatcher.cc
index 5e616b01a17ed217a28cd12bef0998c057a7189e..ac50f0f57c73efc53e30ccafd55b70d5ba586504 100644
--- a/chrome/renderer/prerender/prerender_dispatcher.cc
+++ b/chrome/renderer/prerender/prerender_dispatcher.cc
@@ -174,4 +174,16 @@ void PrerenderDispatcher::abandon(const WebPrerender& prerender) {
   prerenders_.erase(extra_data.prerender_id());
 }
 
+void PrerenderDispatcher::detachRenderer() {
+  // Blink is shutting down, abandon all in-flight prerenders.
+  for (auto it : prerenders_) {
+    const PrerenderExtraData& extra_data =
+        PrerenderExtraData::FromPrerender(it.second);
+    content::RenderThread::Get()->Send(
+        new PrerenderHostMsg_AbandonLinkRelPrerender(
+            extra_data.prerender_id()));
+  }
+  prerenders_.clear();
+}
+
 }  // namespace prerender