Fix initial erroneous navigation in iframe to not add history entry.

content/renderer/render_view_impl.cc

Index: content/renderer/render_view_impl.cc
diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index 01cb2bcc0b8b7a0153100818c456cd04afde8a79..a4d43bb16d0915a2ec2bd4c7acbfc599aca58d7b 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -3559,9 +3559,10 @@ void RenderViewImpl::didStartProvisionalLoad(WebFrame* frame) {
   if (is_top_most) {
     navigation_gesture_ = WebUserGestureIndicator::isProcessingUserGesture() ?
         NavigationGestureUser : NavigationGestureAuto;
-  } else if (frame->parent()->isLoading()) {
-    // Take note of AUTO_SUBFRAME loads here, so that we can know how to
-    // load an error page.  See didFailProvisionalLoad.
+  } else if (ds->replacesCurrentHistoryItem()) {
+    // Subframe navigations that don't add session history items must be
+    // marked with AUTO_SUBFRAME. See also didFailProvisionalLoad for how we
+    // handle loading of error pages.
     document_state->navigation_state()->set_transition_type(
         PAGE_TRANSITION_AUTO_SUBFRAME);
   }