Remove old session history logic.

content/browser/frame_host/render_frame_host_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/render_frame_host_impl.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 1049 matching lines @@
 
 void RenderFrameHostImpl::OnFrameFocused() {
   delegate_->SetFocusedFrame(frame_tree_node_, GetSiteInstance());
 }
 
 void RenderFrameHostImpl::OnOpenURL(const FrameHostMsg_OpenURL_Params& params) {
   GURL validated_url(params.url);
   GetProcess()->FilterURL(false, &validated_url);
 
   if (params.is_history_navigation_in_new_child) {
-    DCHECK(SiteIsolationPolicy::UseSubframeNavigationEntries());
-
     // Try to find a FrameNavigationEntry that matches this frame instead, based
     // on the frame's unique name.  If this can't be found, fall back to the
     // default params using RequestOpenURL below.
     if (frame_tree_node_->navigator()->NavigateNewChildFrame(this,
                                                              validated_url))
       return;
   }
 
   TRACE_EVENT1("navigation", "RenderFrameHostImpl::OpenURL", "url",
                validated_url.possibly_invalid_spec());
@@ skipping 2324 matching lines @@
   // There is no pending NavigationEntry in these cases, so pass 0 as the
   // pending_nav_entry_id. If the previous handle was a prematurely aborted
   // navigation loaded via LoadDataWithBaseURL, propagate the entry id.
   return NavigationHandleImpl::Create(
       params.url, frame_tree_node_, is_renderer_initiated,
       params.was_within_same_page, base::TimeTicks::Now(),
       entry_id_for_data_nav, false);  // started_from_context_menu
 }
 
 }  // namespace content