Ensure that child FrameTreeNodes are deleted after a navigation or crash.

content/browser/renderer_host/render_view_host_impl.cc

 // Copyright (c) 2012 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.
 
 #include "content/browser/renderer_host/render_view_host_impl.h"
 
 #include <set>
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 1370 matching lines @@
   WasResized();
   delegate_->RenderViewReady(this);
 }
 
 void RenderViewHostImpl::OnRenderProcessGone(int status, int exit_code) {
   // Keep the termination status so we can get at it later when we
   // need to know why it died.
   render_view_termination_status_ =
       static_cast<base::TerminationStatus>(status);
 
-  // Reset state.
+  // Reset frame tree state.
+  // TODO(creis): Once subframes can be in different processes, we'll need to
+  // clear just the FrameTreeNodes affected by the crash (and their subtrees).
   main_frame_id_ = -1;
+  delegate_->GetFrameTree()->SwapMainFrame(main_render_frame_host_.get());
 
   // Our base class RenderWidgetHost needs to reset some stuff.
   RendererExited(render_view_termination_status_, exit_code);
 
   delegate_->RenderViewTerminated(this,
                                   static_cast<base::TerminationStatus>(status),
                                   exit_code);
 }
 
 void RenderViewHostImpl::OnDidStartProvisionalLoadForFrame(
@@ skipping 881 matching lines @@
 void RenderViewHostImpl::AttachToFrameTree() {
   FrameTree* frame_tree = delegate_->GetFrameTree();
 
   frame_tree->SwapMainFrame(main_render_frame_host_.get());
   if (main_frame_id() != FrameTreeNode::kInvalidFrameId) {
     frame_tree->OnFirstNavigationAfterSwap(main_frame_id());
   }
 }
 
 }  // namespace content