Revert "Revert 249676 "Have the unload event execute in background on cr...""

content/browser/frame_host/render_frame_host_manager.h

Index: content/browser/frame_host/render_frame_host_manager.h
diff --git a/content/browser/frame_host/render_frame_host_manager.h b/content/browser/frame_host/render_frame_host_manager.h
index 39b6b9f1ff1d899420a88dd39970879c4da2f85c..f1cc81c1a5c4ee79500c67b18ee7d4d390d6cb68 100644
--- a/content/browser/frame_host/render_frame_host_manager.h
+++ b/content/browser/frame_host/render_frame_host_manager.h
@@ -12,6 +12,7 @@
 #include "content/browser/renderer_host/render_view_host_delegate.h"
 #include "content/browser/site_instance_impl.h"
 #include "content/common/content_export.h"
+#include "content/public/browser/global_request_id.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "content/public/common/referrer.h"
@@ -113,6 +114,11 @@ class CONTENT_EXPORT RenderFrameHostManager
     virtual ~Delegate() {}
   };
 
+  // Used with FrameTree::ForEach to delete RenderFrameHosts pending shutdown
+  // from a FrameTreeNode's RenderFrameHostManager. Used during destruction of
+  // WebContentsImpl.
+  static bool ClearRFHsPendingShutdown(FrameTreeNode* node);
+
   // All three delegate pointers must be non-NULL and are not owned by this
   // class.  They must outlive this class. The RenderViewHostDelegate and
   // RenderWidgetHostDelegate are what will be installed into all
@@ -270,6 +276,10 @@ class CONTENT_EXPORT RenderFrameHostManager
   // to a new process after this completes or times out.
   void SwapOutOldPage();
 
+  // Deletes a RenderFrameHost that was pending shutdown.
+  void ClearPendingShutdownRFHForSiteInstance(int32 site_instance_id,
+                                              RenderFrameHostImpl* rfh);
+
  private:
   friend class RenderFrameHostManagerTest;
   friend class TestWebContents;
@@ -440,6 +450,11 @@ class CONTENT_EXPORT RenderFrameHostManager
   typedef base::hash_map<int32, RenderFrameHostImpl*> RenderFrameHostMap;
   RenderFrameHostMap swapped_out_hosts_;
 
+  // A map of RenderFrameHosts pending shutdown.
+  typedef base::hash_map<int32, linked_ptr<RenderFrameHostImpl> >
+      RFHPendingDeleteMap;
+  RFHPendingDeleteMap pending_delete_hosts_;
+
   // The intersitial page currently shown if any, not own by this class
   // (the InterstitialPage is self-owned, it deletes itself when hidden).
   InterstitialPageImpl* interstitial_page_;
@@ -453,6 +468,8 @@ class CONTENT_EXPORT RenderFrameHostManager
   // process as its parent.
   CrossProcessFrameConnector* cross_process_frame_connector_;
 
+  base::WeakPtrFactory<RenderFrameHostManager> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(RenderFrameHostManager);
 };