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

content/common/navigation_params.h

 // Copyright 2014 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_COMMON_NAVIGATION_PARAMS_H_
 #define CONTENT_COMMON_NAVIGATION_PARAMS_H_
 
 #include <stdint.h>
 
 #include <string>
@@ skipping 210 matching lines @@
   RequestNavigationParams();
   RequestNavigationParams(bool is_overriding_user_agent,
                           const std::vector<GURL>& redirects,
                           bool can_load_local_resources,
                           base::Time request_time,
                           const PageState& page_state,
                           int32_t page_id,
                           int nav_entry_id,
                           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_history_list_offset,
                           int current_history_list_offset,
                           int current_history_list_length,
                           bool is_view_source,
                           bool should_clear_history_list);
   RequestNavigationParams(const RequestNavigationParams& other);
   ~RequestNavigationParams();
 
@@ skipping 30 matching lines @@
 
   // For history navigations, this indicates whether the load will stay within
   // the same document.  Defaults to false.
   bool is_same_document_history_load;
 
   // Whether this is a history navigation in a newly created child frame, in
   // which case the browser process is instructing the renderer process to load
   // a URL from a session history item.  Defaults to false.
   bool is_history_navigation_in_new_child;
 
+  // If this is a history navigation, this indicates whether the browser process
+  // is aware of any subframe history items for the given frame.  If not, the
+  // renderer does not need to check with the browser if any subframes are
+  // created during the navigation.
+  // TODO(creis): Expand this to a data structure of unique names and
+  // corresponding PageStates in https://crbug.com/639842.
+  bool has_subtree_history_items;
+
   // Whether the frame being navigated has already committed a real page, which
   // affects how new navigations are classified in the renderer process.
   // This currently is only ever set to true in --site-per-process mode.
   // TODO(creis): Create FrameNavigationEntries by default so this always works.
   bool has_committed_real_load;
 
   // For browser-initiated navigations, this is true if this is a new entry
   // being navigated to. This is false otherwise. TODO(avi): Remove this when
   // the pending entry situation is made sane and the browser keeps them around
   // long enough to match them via nav_entry_id, above.
@@ skipping 52 matching lines @@
   ~NavigationParams();
 
   CommonNavigationParams common_params;
   StartNavigationParams start_params;
   RequestNavigationParams request_params;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_NAVIGATION_PARAMS_H_