cc: Cleanup class/struct forward declarations

cc/tiles/gpu_image_decode_controller.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 CC_TILES_GPU_IMAGE_DECODE_CONTROLLER_H_
 #define CC_TILES_GPU_IMAGE_DECODE_CONTROLLER_H_
 
 #include <memory>
 #include <unordered_map>
 #include <vector>
 
 #include "base/containers/mru_cache.h"
 #include "base/memory/discardable_memory.h"
 #include "base/memory/memory_coordinator_client.h"
 #include "base/synchronization/lock.h"
 #include "base/trace_event/memory_dump_provider.h"
 #include "cc/base/cc_export.h"
 #include "cc/resources/resource_format.h"
 #include "cc/tiles/image_decode_controller.h"
 #include "third_party/skia/include/core/SkRefCnt.h"
 
-class SkImageTextureData;
-
 namespace cc {
 
 class ContextProvider;
 
 // OVERVIEW:
 //
 // GpuImageDecodeController handles the decode and upload of images that will
 // be used by Skia's GPU raster path. It also maintains a cache of these
 // decoded/uploaded images for later re-use.
 //
@@ skipping 293 matching lines @@
 
   // We can't release GPU backed SkImages without holding the context lock,
   // so we add them to this list and defer deletion until the next time the lock
   // is held.
   std::vector<sk_sp<SkImage>> images_pending_deletion_;
 };
 
 }  // namespace cc
 
 #endif  // CC_TILES_GPU_IMAGE_DECODE_CONTROLLER_H_