blimp: Cleanup class/struct forward declarations

blimp/engine/renderer/engine_image_serialization_processor.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 BLIMP_ENGINE_RENDERER_ENGINE_IMAGE_SERIALIZATION_PROCESSOR_H_
 #define BLIMP_ENGINE_RENDERER_ENGINE_IMAGE_SERIALIZATION_PROCESSOR_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "blimp/common/blimp_common_export.h"
 #include "blimp/common/blob_cache/id_util.h"
 #include "blimp/engine/mojo/blob_channel.mojom.h"
 #include "cc/blimp/client_picture_cache.h"
 #include "cc/blimp/engine_picture_cache.h"
 #include "cc/blimp/image_serialization_processor.h"
 #include "third_party/libwebp/webp/encode.h"
 #include "third_party/skia/include/core/SkPixelSerializer.h"
 
-namespace content {
-class RenderFrame;
-}  // class content
-
 namespace blimp {
 namespace engine {
 
 class BlobChannelSenderProxy;
 
 // EngineImageSerializationProcessor provides functionality to serialize
 // and temporarily cache Skia images.
 class BLIMP_COMMON_EXPORT EngineImageSerializationProcessor
     : public cc::ImageSerializationProcessor,
       public SkPixelSerializer {
@@ skipping 23 matching lines @@
   // Reusable output buffer for image encoding.
   WebPMemoryWriter writer_state_;
 
   DISALLOW_COPY_AND_ASSIGN(EngineImageSerializationProcessor);
 };
 
 }  // namespace engine
 }  // namespace blimp
 
 #endif  // BLIMP_ENGINE_RENDERER_ENGINE_IMAGE_SERIALIZATION_PROCESSOR_H_