Remove old session history logic.

content/browser/frame_host/frame_navigation_entry.cc

 // Copyright 2015 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/frame_navigation_entry.h"
 
 #include <utility>
 
 #include "content/common/page_state_serialization.h"
 #include "content/common/site_isolation_policy.h"
@@ skipping 81 matching lines @@
   ExplodedPageState exploded_state;
   if (!DecodePageState(page_state_.ToEncodedData(), &exploded_state))
     return;
 
   item_sequence_number_ = exploded_state.top.item_sequence_number;
   document_sequence_number_ = exploded_state.top.document_sequence_number;
 }
 
 scoped_refptr<ResourceRequestBodyImpl> FrameNavigationEntry::GetPostData()
     const {
-  DCHECK(SiteIsolationPolicy::UseSubframeNavigationEntries());
   if (method_ != "POST")
     return nullptr;
 
   // Generate the body from the PageState.
   ExplodedPageState exploded_state;
   if (!DecodePageState(page_state_.ToEncodedData(), &exploded_state))
     return nullptr;
 
   return exploded_state.top.http_body.request_body;
 }
 
 }  // namespace content