Don't load subframe history items if a client redirect occurs during load.

content/browser/frame_host/render_frame_host_manager.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/render_frame_host_manager.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <utility>
@@ skipping 2299 matching lines @@
     } else {
       // If this is a new WebUI it has never interacted with the existing
       // RenderView so call RenderViewCreated.
       render_frame_host_->pending_web_ui()->RenderViewCreated(
           render_frame_host_->render_view_host());
     }
   }
 }
 
 void RenderFrameHostManager::CancelPending() {
+  CHECK(pending_render_frame_host_);
   TRACE_EVENT1("navigation", "RenderFrameHostManager::CancelPending",
                "FrameTreeNode id", frame_tree_node_->frame_tree_node_id());
   render_frame_host_->ClearPendingWebUI();
 
   bool pending_was_loading = pending_render_frame_host_->is_loading();
   DiscardUnusedFrame(UnsetPendingRenderFrameHost());
   if (pending_was_loading)
     frame_tree_node_->DidStopLoading();
 }
 
@@ skipping 274 matching lines @@
                                              resolved_url)) {
     DCHECK(!dest_instance ||
            dest_instance == render_frame_host_->GetSiteInstance());
     return false;
   }
 
   return true;
 }
 
 }  // namespace content