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

content/browser/frame_host/navigation_entry_impl.cc

 // 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.
 
 #include "content/browser/frame_host/navigation_entry_impl.h"
 
 #include <stddef.h>
 
 #include <queue>
 #include <utility>
@@ skipping 673 matching lines @@
                                has_user_gesture(),
 #endif
                                transferred_global_request_id().child_id,
                                transferred_global_request_id().request_id);
 }
 
 RequestNavigationParams NavigationEntryImpl::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_history_list_offset,
     int current_history_list_offset,
     int current_history_list_length) const {
   // Set the redirect chain to the navigation's redirects, unless returning to a
   // completed navigation (whose previous redirects don't apply).
   std::vector<GURL> redirects;
   if (ui::PageTransitionIsNewNavigation(GetTransitionType())) {
     redirects = GetRedirectChain();
   }
 
   int pending_offset_to_send = pending_history_list_offset;
   int current_offset_to_send = current_history_list_offset;
   int current_length_to_send = current_history_list_length;
   if (should_clear_history_list()) {
     // Set the history list related parameters to the same values a
     // NavigationController would return before its first navigation. This will
     // fully clear the RenderView's view of the session history.
     pending_offset_to_send = -1;
     current_offset_to_send = -1;
     current_length_to_send = 0;
   }
 
   RequestNavigationParams request_params(
       GetIsOverridingUserAgent(), redirects, GetCanLoadLocalResources(),
       base::Time::Now(), frame_entry.page_state(), GetPageID(), GetUniqueID(),
       is_same_document_history_load, is_history_navigation_in_new_child,
-      has_committed_real_load, intended_as_new_entry, pending_offset_to_send,
-      current_offset_to_send, current_length_to_send, IsViewSourceMode(),
-      should_clear_history_list());
+      has_subtree_history_items, has_committed_real_load, intended_as_new_entry,
+      pending_offset_to_send, current_offset_to_send, current_length_to_send,
+      IsViewSourceMode(), should_clear_history_list());
 #if defined(OS_ANDROID)
   if (GetDataURLAsString() &&
       GetDataURLAsString()->size() <= kMaxLengthOfDataURLString) {
     // The number of characters that is enough for validating a data: URI.  From
     // the GURL's POV, the only important part here is scheme, it doesn't check
     // the actual content. Thus we can take only the prefix of the url, to avoid
     // unneeded copying of a potentially long string.
     const size_t kDataUriPrefixMaxLen = 64;
     GURL data_url(std::string(
         GetDataURLAsString()->front_as<char>(),
@@ skipping 104 matching lines @@
   parent_node->children.push_back(
       new NavigationEntryImpl::TreeNode(parent_node, frame_entry));
 }
 
 FrameNavigationEntry* NavigationEntryImpl::GetFrameEntry(
     FrameTreeNode* frame_tree_node) const {
   NavigationEntryImpl::TreeNode* tree_node = FindFrameEntry(frame_tree_node);
   return tree_node ? tree_node->frame_entry.get() : nullptr;
 }
 
+bool NavigationEntryImpl::HasSubtreeHistoryItems(
+    FrameTreeNode* frame_tree_node) const {
+  NavigationEntryImpl::TreeNode* tree_node = FindFrameEntry(frame_tree_node);
+  return tree_node && !tree_node->children.empty();
+}
+
 void NavigationEntryImpl::ClearStaleFrameEntriesForNewFrame(
     FrameTreeNode* frame_tree_node) {
   DCHECK(!frame_tree_node->IsMainFrame());
 
   NavigationEntryImpl::TreeNode* node = nullptr;
   std::queue<NavigationEntryImpl::TreeNode*> work_queue;
   int count = 0;
 
   work_queue.push(root_node());
   while (!work_queue.empty()) {
@@ skipping 47 matching lines @@
       return node;
 
     // Enqueue any children and keep looking.
     for (auto* child : node->children)
       work_queue.push(child);
   }
   return nullptr;
 }
 
 }  // namespace content