Update a comment with a link to a historic source.

content/renderer/render_frame_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/renderer/render_frame_impl.h"
 
 #include <map>
 #include <string>
 
 #include "base/auto_reset.h"
@@ skipping 3790 matching lines @@
     // This message needs to be sent before any of allowScripts(),
     // allowImages(), allowPlugins() is called for the new page, so that when
     // these functions send a ViewHostMsg_ContentBlocked message, it arrives
     // after the FrameHostMsg_DidCommitProvisionalLoad message.
     Send(new FrameHostMsg_DidCommitProvisionalLoad(routing_id_, params));
   } else {
     // Subframe navigation: the type depends on whether this navigation
     // generated a new session history entry. When they do generate a session
     // history entry, it means the user initiated the navigation and we should
     // mark it as such.
-    bool is_history_navigation = commit_type == blink::WebBackForwardCommit;
-    if (is_history_navigation || ds->replacesCurrentHistoryItem())
+    if (commit_type == blink::WebStandardCommit)
+      params.transition = ui::PAGE_TRANSITION_MANUAL_SUBFRAME;
+    else
       params.transition = ui::PAGE_TRANSITION_AUTO_SUBFRAME;
-    else
-      params.transition = ui::PAGE_TRANSITION_MANUAL_SUBFRAME;
 
     DCHECK(!navigation_state->history_list_was_cleared());
     params.history_list_was_cleared = false;
     params.report_type = FrameMsg_UILoadMetricsReportType::NO_REPORT;
 
     // Don't send this message while the subframe is swapped out.
     if (!is_swapped_out())
       Send(new FrameHostMsg_DidCommitProvisionalLoad(routing_id_, params));
   }
 
@@ skipping 615 matching lines @@
 
 #if defined(ENABLE_BROWSER_CDMS)
 RendererCdmManager* RenderFrameImpl::GetCdmManager() {
   if (!cdm_manager_)
     cdm_manager_ = new RendererCdmManager(this);
   return cdm_manager_;
 }
 #endif  // defined(ENABLE_BROWSER_CDMS)
 
 }  // namespace content