media: Cleanup class/struct forward declarations

media/blink/webencryptedmediaclient_impl.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 MEDIA_BLINK_WEBENCRYPTEDMEDIACLIENT_IMPL_H_
 #define MEDIA_BLINK_WEBENCRYPTEDMEDIACLIENT_IMPL_H_
 
 #include <memory>
 #include <string>
 
 #include "base/callback.h"
 #include "base/containers/scoped_ptr_hash_map.h"
 #include "base/memory/weak_ptr.h"
 #include "media/blink/key_system_config_selector.h"
 #include "media/blink/media_blink_export.h"
 #include "third_party/WebKit/public/platform/WebEncryptedMediaClient.h"
 
 namespace blink {
 
 class WebContentDecryptionModuleResult;
 struct WebMediaKeySystemConfiguration;
 class WebSecurityOrigin;
 
 }  // namespace blink
 
 namespace media {
 
 struct CdmConfig;
 class CdmFactory;
-class KeySystems;
 class MediaPermission;
 
 class MEDIA_BLINK_EXPORT WebEncryptedMediaClientImpl
     : public blink::WebEncryptedMediaClient {
  public:
   WebEncryptedMediaClientImpl(
       base::Callback<bool(void)> are_secure_codecs_supported_cb,
       CdmFactory* cdm_factory,
       MediaPermission* media_permission);
   ~WebEncryptedMediaClientImpl() override;
@@ skipping 37 matching lines @@
 
   base::Callback<bool(void)> are_secure_codecs_supported_cb_;
   CdmFactory* cdm_factory_;
   KeySystemConfigSelector key_system_config_selector_;
   base::WeakPtrFactory<WebEncryptedMediaClientImpl> weak_factory_;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BLINK_WEBENCRYPTEDMEDIACLIENT_IMPL_H_