Fix user agent overridding with PlzNavigate.

content/browser/frame_host/interstitial_page_impl.h

 // 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.
 
 #ifndef CONTENT_BROWSER_FRAME_HOST_INTERSTITIAL_PAGE_IMPL_H_
 #define CONTENT_BROWSER_FRAME_HOST_INTERSTITIAL_PAGE_IMPL_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 79 matching lines @@
   bool pause_throbber() const { return pause_throbber_; }
 
   // TODO(nasko): This should move to InterstitialPageNavigatorImpl, but in
   // the meantime make it public, so it can be called directly.
   void DidNavigate(
       RenderViewHost* render_view_host,
       const FrameHostMsg_DidCommitProvisionalLoad_Params& params);
 
   // NavigatorDelegate implementation.
   WebContents* OpenURL(const OpenURLParams& params) override;
+  const std::string& GetUserAgentOverride() const override;
 
  protected:
   // NotificationObserver method:
   void Observe(int type,
                const NotificationSource& source,
                const NotificationDetails& details) override;
 
   // RenderFrameHostDelegate implementation:
   bool OnMessageReceived(RenderFrameHostImpl* render_frame_host,
                          const IPC::Message& message) override;
@@ skipping 189 matching lines @@
   scoped_refptr<SessionStorageNamespace> session_storage_namespace_;
 
   base::WeakPtrFactory<InterstitialPageImpl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(InterstitialPageImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_INTERSTITIAL_PAGE_IMPL_H_