Catch empty PageStates on history navigations earlier.

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 <utility>
 #include <vector>
@@ skipping 5672 matching lines @@
                                    WebString::fromUTF8(i.values()));
       }
     }
 
     if (common_params.method == "POST" && !browser_side_navigation &&
         common_params.post_data) {
       request.setHTTPBody(
           GetWebHTTPBodyForRequestBody(common_params.post_data));
     }
 
-    // A session history navigation should have been accompanied by state.
-    // TODO(creis): This is known to be failing in UseSubframeNavigationEntries
-    // in https://crbug.com/568703, when the PageState on a FrameNavigationEntry
-    // is unexpectedly empty.  Until the cause is found, keep this as a DCHECK
-    // and load the URL without PageState.
-    DCHECK_EQ(request_params.page_id, -1);
-
     should_load_request = true;
   }
 
   if (should_load_request) {
     // PlzNavigate: check if the navigation being committed originated as a
     // client redirect.
     bool is_client_redirect =
         browser_side_navigation
             ? !!(common_params.transition & ui::PAGE_TRANSITION_CLIENT_REDIRECT)
             : false;
@@ skipping 720 matching lines @@
   // event target. Potentially a Pepper plugin will receive the event.
   // In order to tell whether a plugin gets the last mouse event and which it
   // is, we set |pepper_last_mouse_event_target_| to null here. If a plugin gets
   // the event, it will notify us via DidReceiveMouseEvent() and set itself as
   // |pepper_last_mouse_event_target_|.
   pepper_last_mouse_event_target_ = nullptr;
 #endif
 }
 
 }  // namespace content