OOPIF: Fix subframe back/forward after recreating FTNs (try #2).

content/browser/frame_host/frame_navigation_entry.h

Index: content/browser/frame_host/frame_navigation_entry.h
diff --git a/content/browser/frame_host/frame_navigation_entry.h b/content/browser/frame_host/frame_navigation_entry.h
index e93eb010a44a061fb2d6c0d774c7b1883569d7c7..256cd266a0f2dab43833c27c717c28ea0689d68b 100644
--- a/content/browser/frame_host/frame_navigation_entry.h
+++ b/content/browser/frame_host/frame_navigation_entry.h
@@ -15,7 +15,8 @@
 
 namespace content {
 
-// Represents a session history item for a particular frame.
+// Represents a session history item for a particular frame.  It is matched with
+// corresponding FrameTreeNodes using unique name (or by the root position).
 //
 // This class is refcounted and can be shared across multiple NavigationEntries.
 // For now, it is owned by a single NavigationEntry and only tracks the main
@@ -28,9 +29,8 @@ namespace content {
 class CONTENT_EXPORT FrameNavigationEntry
     : public base::RefCounted<FrameNavigationEntry> {
  public:
-  explicit FrameNavigationEntry(int frame_tree_node_id);
-  FrameNavigationEntry(int frame_tree_node_id,
-                       const std::string& frame_unique_name,
+  FrameNavigationEntry();
+  FrameNavigationEntry(const std::string& frame_unique_name,
                        int64_t item_sequence_number,
                        int64_t document_sequence_number,
                        scoped_refptr<SiteInstanceImpl> site_instance,
@@ -54,17 +54,6 @@ class CONTENT_EXPORT FrameNavigationEntry
                    const std::string& method,
                    int64_t post_id);
 
-  // The ID of the FrameTreeNode this entry is for.  -1 for the main frame,
-  // since we don't always know the FrameTreeNode ID when creating the overall
-  // NavigationEntry.
-  // TODO(creis): Consider removing |frame_tree_node_id| in favor of
-  // |frame_unique_name|, if we can move unique name computation to the browser
-  // process.
-  int frame_tree_node_id() const { return frame_tree_node_id_; }
-  void set_frame_tree_node_id(int frame_tree_node_id) {
-    frame_tree_node_id_ = frame_tree_node_id;
-  }
-
   // The unique name of the frame this entry is for.  This is a stable name for
   // the frame based on its position in the tree and relation to other named
   // frames, which does not change after cross-process navigations or restores.
@@ -129,7 +118,6 @@ class CONTENT_EXPORT FrameNavigationEntry
   // WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING
 
   // See the accessors above for descriptions.
-  int frame_tree_node_id_;
   std::string frame_unique_name_;
   int64_t item_sequence_number_;
   int64_t document_sequence_number_;