Do not reset navigation state when BeforeUnload is cancelled by a commit

content/browser/web_contents/web_contents_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/web_contents/web_contents_impl.h"
 
 #include <stddef.h>
 
 #include <cmath>
 #include <utility>
@@ skipping 4659 matching lines @@
                                      int render_frame_id,
                                      IPC::Message* reply_msg,
                                      bool dialog_was_suppressed,
                                      bool success,
                                      const base::string16& user_input) {
   RenderFrameHostImpl* rfh = RenderFrameHostImpl::FromID(render_process_id,
                                                          render_frame_id);
   last_dialog_suppressed_ = dialog_was_suppressed;
 
   if (is_showing_before_unload_dialog_ && !success) {
-    if (rfh)
+    // It is possible for the RenderFrameHost to have been swapped out in the

[nasko, 2016/03/29 20:19:06]

nit: Let's start avoiding using "swapped out" as terminology. Suggestion: "It is
possible for the current RenderFrameHost to have changed in the meantime."

[clamy, 2016/03/30 13:31:11]

Done.

+    // meantime. Do not reset the navigation state in that case.
+    if (rfh && rfh == rfh->frame_tree_node()->current_frame_host()) {
       rfh->frame_tree_node()->BeforeUnloadCanceled();
-    controller_.DiscardNonCommittedEntries();
+      controller_.DiscardNonCommittedEntries();
+    }
 
     FOR_EACH_OBSERVER(WebContentsObserver, observers_,
                       BeforeUnloadDialogCancelled());
   }
 
   is_showing_before_unload_dialog_ = false;
   if (rfh) {
     rfh->JavaScriptDialogClosed(reply_msg, success, user_input,
                                 dialog_was_suppressed);
   } else {
@@ skipping 132 matching lines @@
   else
     WasHidden();
 }
 
 void WebContentsImpl::SetJavaScriptDialogManagerForTesting(
     JavaScriptDialogManager* dialog_manager) {
   dialog_manager_ = dialog_manager;
 }
 
 }  // namespace content