With --site-per-process, avoid a crash when a subframe process goes away.

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 <string>
 
 #include "base/callback.h"
@@ skipping 74 matching lines @@
                    int64 frame_id);
   void SetFrameUrl(int64 frame_id, const GURL& url);
 
   // Clears process specific-state after a main frame process swap.
   // This destroys most of the frame tree but retains the root node so that
   // navigation state may be kept on it between process swaps. Used to
   // support bookkeeping for top-level navigations.
   // TODO(creis): Look into how we can remove the need for this method.
   void ResetForMainFrameSwap();
 
+  // Update the frame tree after a process exits.  Any nodes currently using the
+  // given |render_view_host| will lose all their children.
+  void RenderProcessGone(RenderViewHost* render_view_host);
+
   // Convenience accessor for the main frame's RenderFrameHostImpl.
   RenderFrameHostImpl* GetMainFrame() const;
 
   // Allows a client to listen for frame removal.  The listener should expect
   // to receive the RenderViewHostImpl containing the frame and the renderer-
   // specific frame ID of the removed frame.
   // TODO(creis): These parameters will later change to be the RenderFrameHost.
   void SetFrameRemoveListener(
       const base::Callback<void(RenderViewHostImpl*, int64)>& on_frame_removed);
 
@@ skipping 55 matching lines @@
   scoped_ptr<FrameTreeNode> root_;
 
   base::Callback<void(RenderViewHostImpl*, int64)> on_frame_removed_;
 
   DISALLOW_COPY_AND_ASSIGN(FrameTree);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_FRAME_TREE_H_