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

chrome/browser/extensions/chrome_extensions_browser_client.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 CHROME_BROWSER_EXTENSIONS_CHROME_EXTENSIONS_BROWSER_CLIENT_H_
 #define CHROME_BROWSER_EXTENSIONS_CHROME_EXTENSIONS_BROWSER_CLIENT_H_
 
 #include <memory>
 #include <string>
 #include <vector>
@@ skipping 104 matching lines @@
                                      ViewType view_type) override;
   scoped_refptr<update_client::UpdateClient> CreateUpdateClient(
       content::BrowserContext* context) override;
   std::unique_ptr<ExtensionApiFrameIdMapHelper>
   CreateExtensionApiFrameIdMapHelper(
       ExtensionApiFrameIdMap* map) override;
   std::unique_ptr<content::BluetoothChooser> CreateBluetoothChooser(
       content::RenderFrameHost* frame,
       const content::BluetoothChooser::EventHandler& event_handler) override;
   bool IsActivityLoggingEnabled(content::BrowserContext* context) override;
+  extensions::ExtensionNavigationUIData* GetExtensionNavigationUIData(
+      net::URLRequest* request) override;
   KioskDelegate* GetKioskDelegate() override;
 
  private:
   friend struct base::DefaultLazyInstanceTraits<ChromeExtensionsBrowserClient>;
 
   // Support for ProcessManager.
   std::unique_ptr<ChromeProcessManagerDelegate> process_manager_delegate_;
 
   // Client for API implementations.
   std::unique_ptr<ChromeExtensionsAPIClient> api_client_;
 
   std::unique_ptr<ChromeComponentExtensionResourceManager> resource_manager_;
 
   std::unique_ptr<ExtensionCache> extension_cache_;
 
   std::unique_ptr<KioskDelegate> kiosk_delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeExtensionsBrowserClient);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_CHROME_EXTENSIONS_BROWSER_CLIENT_H_