media: Cleanup class/struct forward declarations

media/base/pipeline_impl.h

 // Copyright (c) 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 MEDIA_BASE_PIPELINE_IMPL_H_
 #define MEDIA_BASE_PIPELINE_IMPL_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/thread_checker.h"
 #include "media/base/media_export.h"
 #include "media/base/pipeline.h"
 
 namespace base {
 class SingleThreadTaskRunner;
 }
 
 namespace media {
 
 class MediaLog;
-class TextRenderer;
 
 // Pipeline runs the media pipeline.  Filters are created and called on the
 // task runner injected into this object. Pipeline works like a state
 // machine to perform asynchronous initialization, pausing, seeking and playing.
 //
 // Here's a state diagram that describes the lifetime of this object.
 //
 //   [ *Created ]                       [ Any State ]
 //         | Start()                         | Stop() / SetError()
 //         V                                 V
@@ skipping 141 matching lines @@
 
   base::ThreadChecker thread_checker_;
   base::WeakPtrFactory<PipelineImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PipelineImpl);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_PIPELINE_IMPL_H_