Fix nullptr deref in maybeRenderFallbackContent()

third_party/WebKit/Source/web/WebLocalFrameImpl.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 248 matching lines @@
   void LoadData(const WebData&,
                 const WebString& mime_type,
                 const WebString& text_encoding,
                 const WebURL& base_url,
                 const WebURL& unreachable_url,
                 bool replace,
                 WebFrameLoadType,
                 const WebHistoryItem&,
                 WebHistoryLoadType,
                 bool is_client_redirect) override;
-  bool MaybeRenderFallbackContent(const WebURLError&) const override;
+  FallbackContentResult MaybeRenderFallbackContent(
+      const WebURLError&) const override;
   void ReportContentSecurityPolicyViolation(
       const blink::WebContentSecurityPolicyViolation&) override;
   bool IsLoading() const override;
   bool IsNavigationScheduledWithin(double interval) const override;
   void SetCommittedFirstRealLoad() override;
   void SetHasReceivedUserGesture() override;
   void BlinkFeatureUsageReport(const std::set<int>& features) override;
   void MixedContentFound(const WebURL& main_resource_url,
                          const WebURL& mixed_content_url,
                          WebURLRequest::RequestContext,
@@ skipping 241 matching lines @@
 
 DEFINE_TYPE_CASTS(WebLocalFrameImpl,
                   WebFrame,
                   frame,
                   frame->IsWebLocalFrame(),
                   frame.IsWebLocalFrame());
 
 }  // namespace blink
 
 #endif