Remove use of page id for forking callback.

content/renderer/render_frame_impl.cc

Index: content/renderer/render_frame_impl.cc
diff --git a/content/renderer/render_frame_impl.cc b/content/renderer/render_frame_impl.cc
index b44691dc57a9f4df6a18592fbf89559507476de8..1c4aa7548e0d4d3e4918faf161dce2b4b31a7e6d 100644
--- a/content/renderer/render_frame_impl.cc
+++ b/content/renderer/render_frame_impl.cc
@@ -4286,7 +4286,7 @@ WebNavigationPolicy RenderFrameImpl::DecidePolicyForNavigation(
     // handled by the browser so that ordinary renderer processes don't get
     // blessed with file permissions.
     int cumulative_bindings = RenderProcess::current()->GetEnabledBindings();
-    bool is_initial_navigation = render_view_->page_id_ == -1;
+    bool is_initial_navigation = render_view_->history_list_length_ == 0;
     bool should_fork = HasWebUIScheme(url) || HasWebUIScheme(old_url) ||
         (cumulative_bindings & BINDINGS_POLICY_WEB_UI) ||
         url.SchemeIs(kViewSourceScheme) ||