extensions: Cleanup class/struct fwd declarations

extensions/shell/renderer/shell_content_renderer_client.h

 // Copyright 2014 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 EXTENSIONS_SHELL_RENDERER_SHELL_CONTENT_RENDERER_CLIENT_H_
 #define EXTENSIONS_SHELL_RENDERER_SHELL_CONTENT_RENDERER_CLIENT_H_
 
 #include <memory>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "content/public/renderer/content_renderer_client.h"
 
 namespace blink {
 class WebURL;
 }  // namespace blink
 
 namespace extensions {
 
 class Dispatcher;
 class DispatcherDelegate;
 class ExtensionsClient;
 class ExtensionsGuestViewContainerDispatcher;
 class ShellExtensionsRendererClient;
-class ShellRendererMainDelegate;
 
 // Renderer initialization and runtime support for app_shell.
 class ShellContentRendererClient : public content::ContentRendererClient {
  public:
   ShellContentRendererClient();
   ~ShellContentRendererClient() override;
 
   // content::ContentRendererClient implementation:
   void RenderThreadStarted() override;
   void RenderFrameCreated(content::RenderFrame* render_frame) override;
@@ skipping 30 matching lines @@
   std::unique_ptr<Dispatcher> extension_dispatcher_;
   std::unique_ptr<ExtensionsGuestViewContainerDispatcher>
       guest_view_container_dispatcher_;
 
   DISALLOW_COPY_AND_ASSIGN(ShellContentRendererClient);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_SHELL_RENDERER_SHELL_CONTENT_RENDERER_CLIENT_H_