extensions: Cleanup class/struct fwd declarations

extensions/renderer/api/display_source/wifi_display/wifi_display_media_manager.h

 // Copyright 2016 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_RENDERER_API_DISPLAY_SOURCE_WIFI_DISPLAY_WIFI_DISPLAY_MEDIA_MANAGER_H_
 #define EXTENSIONS_RENDERER_API_DISPLAY_SOURCE_WIFI_DISPLAY_WIFI_DISPLAY_MEDIA_MANAGER_H_
 
 #include <memory>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/memory/weak_ptr.h"
 #include "extensions/common/mojo/wifi_display_session_service.mojom.h"
 #include "extensions/renderer/api/display_source/wifi_display/wifi_display_media_packetizer.h"
 #include "extensions/renderer/api/display_source/wifi_display/wifi_display_video_encoder.h"
 #include "third_party/WebKit/public/platform/WebMediaStreamTrack.h"
 #include "third_party/wds/src/libwds/public/media_manager.h"
 
 namespace service_manager {
 class InterfaceProvider;
 }
 
 namespace extensions {
 class WiFiDisplayAudioSink;
 class WiFiDisplayVideoSink;
 class WiFiDisplayMediaPipeline;
-class WiFiDisplaySessionService;
 
 class WiFiDisplayMediaManager : public wds::SourceMediaManager {
  public:
   using ErrorCallback = base::Callback<void(const std::string&)>;
 
   WiFiDisplayMediaManager(
       const blink::WebMediaStreamTrack& video_track,
       const blink::WebMediaStreamTrack& audio_track,
       const std::string& sink_ip_address,
       service_manager::InterfaceProvider* interface_provider,
@@ skipping 54 matching lines @@
   mutable std::string session_id_;  // Lazily initialized.
 
   base::WeakPtrFactory<WiFiDisplayMediaManager> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WiFiDisplayMediaManager);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_API_DISPLAY_SOURCE_WIFI_DISPLAY_WIFI_DISPLAY_MEDIA_MANAGER_H_