cc: Remove unused proto conversion code.

cc/test/serialization_test_utils.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_TEST_SERIALIZATION_TEST_UTILS_H_
 #define CC_TEST_SERIALIZATION_TEST_UTILS_H_
 
 #include "base/macros.h"
 
 namespace cc {
 class CompositorStateDeserializer;
+class FakePictureLayer;
 class Layer;
 class LayerTree;
+class SolidColorScrollbarLayer;
 
 void VerifySerializedTreesAreIdentical(
     LayerTree* engine_layer_tree,
     LayerTree* client_layer_tree,
     CompositorStateDeserializer* compositor_state_deserializer);
 
 void VerifySerializedLayersAreIdentical(
     Layer* engine_layer,
-    Layer* client_layer,
+    CompositorStateDeserializer* compositor_state_deserializer);
+
+void VerifySerializedScrollbarLayersAreIdentical(
+    SolidColorScrollbarLayer* engine_layer,
+    CompositorStateDeserializer* compositor_state_deserializer);
+
+void VerifySerializedPictureLayersAreIdentical(
+    FakePictureLayer* engine_layer,
     CompositorStateDeserializer* compositor_state_deserializer);
 
 }  // namespace cc
 
 #endif  // CC_TEST_SERIALIZATION_TEST_UTILS_H_