Fix user agent overridding with PlzNavigate.

content/browser/web_contents/web_contents_impl.cc

 // Copyright (c) 2012 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/web_contents/web_contents_impl.h"
 
 #include <stddef.h>
 
 #include <cmath>
 #include <utility>
@@ skipping 3408 matching lines @@
     return true;
   return delegate_->ShouldTransferNavigation(is_main_frame_navigation);
 }
 
 bool WebContentsImpl::ShouldPreserveAbortedURLs() {
   if (!delegate_)
     return false;
   return delegate_->ShouldPreserveAbortedURLs(this);
 }
 
+const std::string& WebContentsImpl::GetNavigationUserAgentOverride() {
+  return renderer_preferences_.user_agent_override;
+}
+
 void WebContentsImpl::DidNavigateMainFramePreCommit(
     bool navigation_is_within_page) {
   // Ensure fullscreen mode is exited before committing the navigation to a
   // different page.  The next page will not start out assuming it is in
   // fullscreen mode.
   if (navigation_is_within_page) {
     // No page change?  Then, the renderer and browser can remain in fullscreen.
     return;
   }
   if (IsFullscreenForCurrentTab())
@@ skipping 1955 matching lines @@
     RenderViewHost* render_view_host = RenderViewHost::From(render_widget_host);
     if (!render_view_host)
       continue;
     render_view_host_set.insert(render_view_host);
   }
   for (RenderViewHost* render_view_host : render_view_host_set)
     render_view_host->OnWebkitPreferencesChanged();
 }
 
 }  // namespace content