Remove existing FrameNavigationEntry when new named frame is added.

content/browser/frame_host/navigation_entry_impl.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_NAVIGATION_ENTRY_IMPL_H_
 #define CONTENT_BROWSER_FRAME_HOST_NAVIGATION_ENTRY_IMPL_H_
 
 #include <stdint.h>
 
 #include "base/macros.h"
@@ skipping 215 matching lines @@
 
   // Returns the FrameNavigationEntry corresponding to |frame_tree_node|, if
   // there is one in this NavigationEntry.
   FrameNavigationEntry* GetFrameEntry(FrameTreeNode* frame_tree_node) const;
 
   // Removes subframe FrameNavigationEntries below the item corresponding to
   // |frame_tree_node| (if any).  This is necessary after server redirects
   // during session history navigations, when the child items no longer apply.
   void ClearChildren(FrameTreeNode* frame_tree_node);
 
+  // Removes subframe FrameNavigationEntry matching the |frame_unique_name| and

[Charlie Reis, 2016/07/27 22:48:28]

nit: Removes the
nit: ... |frame_unique_name|, if any, and...

Maybe we should also document that this will remove all such FNEs, but that we
expect there to be at most 1 (and will DCHECK otherwise).

[nasko, 2016/07/29 15:52:22]

What does documenting this here give us? It will be adding description of what
bugs we might have, which the DCHECK is aimed at catching in the first place.

[Charlie Reis, 2016/07/29 17:21:35]

I think it matters for potential callers of the method.  For example, this
method would not guarantee the current bug is fixed if it were implemented as
described (i.e., it stopped after the first one), because there could still be
more colliding FNEs in the tree.

We don't need to mention the DCHECK, but I think we can still clarify:

Removes any subframe FrameNavigationEntries that match the unique name of
|frame_tree_node|, and all of their children.  We expect there to be at most
one, since we avoid collisions but leave old FrameNavigationEntries in the tree
after their frame has been detached.

[nasko, 2016/08/01 20:42:15]

Done.

+  // all of its children.
+  void ClearNamedFrameEntries(const std::string& frame_unique_name);
+
   void set_unique_id(int unique_id) {
     unique_id_ = unique_id;
   }
 
   // The SiteInstance represents which pages must share processes. This is a
   // reference counted pointer to a shared SiteInstance.
   //
   // Note that the SiteInstance should usually not be changed after it is set,
   // but this may happen if the NavigationEntry was cloned and needs to use a
   // different SiteInstance.
@@ skipping 276 matching lines @@
   // persisted, unless specific data is taken out/put back in at save/restore
   // time (see TabNavigation for an example of this).
   std::map<std::string, base::string16> extra_data_;
 
   DISALLOW_COPY_AND_ASSIGN(NavigationEntryImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_NAVIGATION_ENTRY_IMPL_H_