Notify the renderer if a history navigation has no subframe items.

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 166 matching lines @@
       const GURL& dest_url,
       const Referrer& dest_referrer,
       FrameMsg_Navigate_Type::Value navigation_type,
       LoFiState lofi_state,
       const base::TimeTicks& navigation_start) const;
   StartNavigationParams ConstructStartNavigationParams() const;
   RequestNavigationParams ConstructRequestNavigationParams(
       const FrameNavigationEntry& frame_entry,
       bool is_same_document_history_load,
       bool is_history_navigation_in_new_child,
+      bool has_subtree_history_items,
       bool has_committed_real_load,
       bool intended_as_new_entry,
       int pending_offset_to_send,
       int current_offset_to_send,
       int current_length_to_send) const;
 
   // Once a navigation entry is committed, we should no longer track several
   // pieces of non-persisted state, as documented on the members below.
   // |frame_entry| is the FrameNavigationEntry for the frame that committed
   // the navigation. It can be null.
@@ skipping 23 matching lines @@
       const GURL& url,
       const Referrer& referrer,
       const PageState& page_state,
       const std::string& method,
       int64_t post_id);
 
   // Returns the FrameNavigationEntry corresponding to |frame_tree_node|, if
   // there is one in this NavigationEntry.
   FrameNavigationEntry* GetFrameEntry(FrameTreeNode* frame_tree_node) const;
 
+  // Returns whether the TreeNode associated with |frame_tree_node| has any
+  // children.  If not, the renderer process does not need to ask the browser
+  // when new subframes are created during a back/forward navigation.
+  // TODO(creis): Send a data structure with all unique names in the subtree,
+  // along with any corresponding same-process PageStates.  The renderer only
+  // needs to ask the browser process to handle the cross-process cases.
+  // See https://crbug.com/639842.
+  bool HasSubtreeHistoryItems(FrameTreeNode* frame_tree_node) const;
+
   // Removes any subframe FrameNavigationEntries that match the unique name of
   // |frame_tree_node|, and all of their children. There should be at most one,
   // since collisions are avoided but leave old FrameNavigationEntries in the
   // tree after their frame has been detached.
   void ClearStaleFrameEntriesForNewFrame(FrameTreeNode* frame_tree_node);
 
   void set_unique_id(int unique_id) {
     unique_id_ = unique_id;
   }
 
@@ skipping 282 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_