Ensure that modal dialogs from subframes can be cleaned up correctly.

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 1159 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 frame tree state associated with this process.
+  // Reset frame tree state associated with this process.  This must happen
+  // before RenderViewTerminated because observers expect the subframes of any
+  // affected frames to be cleared first.
   delegate_->GetFrameTree()->RenderProcessGone(this);
 
   // 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);
 }
 
@@ skipping 570 matching lines @@
   return true;
 }
 
 void RenderViewHostImpl::AttachToFrameTree() {
   FrameTree* frame_tree = delegate_->GetFrameTree();
 
   frame_tree->ResetForMainFrameSwap();
 }
 
 }  // namespace content