cc: Cleanup class/struct forward declarations

cc/test/layer_tree_pixel_test.h

 // Copyright 2013 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_TEST_LAYER_TREE_PIXEL_TEST_H_
 #define CC_TEST_LAYER_TREE_PIXEL_TEST_H_
 
 #include <memory>
 #include <vector>
 
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "cc/resources/single_release_callback.h"
 #include "cc/test/layer_tree_test.h"
 #include "ui/gl/gl_implementation.h"
 
 class SkBitmap;
 
-namespace gpu {
-class GLInProcessContext;
-}
-
 namespace cc {
 class CopyOutputRequest;
 class CopyOutputResult;
-class LayerTreeHost;
 class PixelComparator;
 class SolidColorLayer;
 class TextureLayer;
 class TextureMailbox;
 
 class LayerTreePixelTest : public LayerTreeTest {
  public:
   enum PixelTestType {
     PIXEL_TEST_GL,
     PIXEL_TEST_SOFTWARE,
@@ skipping 68 matching lines @@
   base::FilePath ref_file_;
   std::unique_ptr<SkBitmap> result_bitmap_;
   std::vector<scoped_refptr<TextureLayer>> texture_layers_;
   int pending_texture_mailbox_callbacks_;
   gfx::Size enlarge_texture_amount_;
 };
 
 }  // namespace cc
 
 #endif  // CC_TEST_LAYER_TREE_PIXEL_TEST_H_