Always swap with a replacement proxy in OnSwapOut.

content/browser/frame_host/frame_tree.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_FRAME_HOST_FRAME_TREE_H_
 #define CONTENT_BROWSER_FRAME_HOST_FRAME_TREE_H_
 
 #include <stdint.h>
 
 #include <iterator>
@@ skipping 193 matching lines @@
   void ReplicatePageFocus(bool is_focused);
 
   // Updates page-level focus for this FrameTree in the subframe renderer
   // identified by |instance|.
   void SetPageFocus(SiteInstance* instance, bool is_focused);
 
  private:
   friend class FrameTreeTest;
   FRIEND_TEST_ALL_PREFIXES(RenderFrameHostImplBrowserTest, RemoveFocusedFrame);
   typedef base::hash_map<int, RenderViewHostImpl*> RenderViewHostMap;
-  typedef std::multimap<int, RenderViewHostImpl*> RenderViewHostMultiMap;
 
   // Returns a range to iterate over all FrameTreeNodes in the frame tree in
   // breadth-first traversal order, skipping the subtree rooted at
   // |node_to_skip|.
   NodeRange NodesExcept(FrameTreeNode* node_to_skip);
 
   // These delegates are installed into all the RenderViewHosts and
   // RenderFrameHosts that we create.
   RenderFrameHostDelegate* render_frame_delegate_;
   RenderViewHostDelegate* render_view_delegate_;
   RenderWidgetHostDelegate* render_widget_delegate_;
   RenderFrameHostManager::Delegate* manager_delegate_;
 
   // Map of SiteInstance ID to a RenderViewHost.  This allows us to look up the
   // RenderViewHost for a given SiteInstance when creating RenderFrameHosts.
   // Combined with the refcount on RenderViewHost, this allows us to call
   // Shutdown on the RenderViewHost and remove it from the map when no more
   // RenderFrameHosts are using it.
   //
   // Must be declared before |root_| so that it is deleted afterward.  Otherwise
   // the map will be cleared before we delete the RenderFrameHosts in the tree.
   RenderViewHostMap render_view_host_map_;
 
-  // Map of SiteInstance ID to RenderViewHosts that are pending shutdown. The
-  // renderers of these RVH are currently executing the unload event in
-  // background. When the SwapOutACK is received, they will be deleted. In the
-  // meantime, they are kept in this map, as they should not be reused (part of
-  // their state is already gone away).
-  RenderViewHostMultiMap render_view_host_pending_shutdown_map_;
-
   // This is an owned ptr to the root FrameTreeNode, which never changes over
   // the lifetime of the FrameTree. It is not a scoped_ptr because we need the
   // pointer to remain valid even while the FrameTreeNode is being destroyed,
   // since it's common for a node to test whether it's the root node.
   FrameTreeNode* root_;
 
   int focused_frame_tree_node_id_;
 
   base::Callback<void(RenderFrameHost*)> on_frame_removed_;
 
   // Overall load progress.
   double load_progress_;
 
   DISALLOW_COPY_AND_ASSIGN(FrameTree);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_FRAME_TREE_H_