Clean up unload-related state after the ack is received.

content/browser/renderer_host/render_view_host.cc

Index: content/browser/renderer_host/render_view_host.cc
diff --git a/content/browser/renderer_host/render_view_host.cc b/content/browser/renderer_host/render_view_host.cc
index 40792b1a501f8cc9287fbb36dfc559b3ddb4a089..df5f1e1990cd804ae3f62cb1573fe860468296ea 100644
--- a/content/browser/renderer_host/render_view_host.cc
+++ b/content/browser/renderer_host/render_view_host.cc
@@ -293,8 +293,9 @@ void RenderViewHost::FirePageBeforeUnload(bool for_cross_site_transition) {
 void RenderViewHost::ClosePage(bool for_cross_site_transition,
                                int new_render_process_host_id,
                                int new_request_id) {
-  // In most cases, this will not be set to false afterward.  Either the tab
-  // will be closed, or a pending RenderViewHost will replace this one.
+  // This will be set back to false in OnClosePageACK, just before we close the
+  // tab or replace it with a pending RVH.  There are some cases (such as 204
+  // errors) where we'll continue to show this RVH.
   is_waiting_for_unload_ack_ = true;
   // Start the hang monitor in case the renderer hangs in the unload handler.
   StartHangMonitorTimeout(TimeDelta::FromMilliseconds(kUnloadTimeoutMS));
@@ -320,6 +321,18 @@ void RenderViewHost::ClosePage(bool for_cross_site_transition,
   }
 }
 
+void RenderViewHost::OnClosePageACK(bool for_cross_site_transition) {
+  StopHangMonitorTimeout();
+  is_waiting_for_unload_ack_ = false;
+
+  // If this ClosePageACK is not for a cross-site transition, then it is for an
+  // attempt to close the tab.  We have now finished the unload handler and can
+  // proceed with closing the tab.
+  if (!for_cross_site_transition) {
+    ClosePageIgnoringUnloadEvents();
+  }
+}
+
 void RenderViewHost::ClosePageIgnoringUnloadEvents() {
   StopHangMonitorTimeout();
   is_waiting_for_beforeunload_ack_ = false;