Make sure the default CSP is used for <webview> with PlzNavigate.

extensions/browser/extensions_browser_client.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 "extensions/browser/extensions_browser_client.h"
 
 #include "base/logging.h"
 #include "components/update_client/update_client.h"
 #include "extensions/browser/extension_api_frame_id_map.h"
 #include "extensions/browser/extension_error.h"
@@ skipping 29 matching lines @@
     content::BrowserContext* context,
     std::unique_ptr<ExtensionError> error) {
   LOG(ERROR) << error->GetDebugString();
 }
 
 bool ExtensionsBrowserClient::IsActivityLoggingEnabled(
     content::BrowserContext* context) {
   return false;
 }
 
+ExtensionNavigationUIData*
+ExtensionsBrowserClient::GetExtensionNavigationUIData(
+    net::URLRequest* request) {
+  return nullptr;
+}
+
 ExtensionsBrowserClient* ExtensionsBrowserClient::Get() {
   return g_client;
 }
 
 void ExtensionsBrowserClient::Set(ExtensionsBrowserClient* client) {
   g_client = client;
 }
 
 }  // namespace extensions