cc: Set up the framework to restrict access to Layer internals.

cc/trees/tree_synchronizer_unittest.cc

 // Copyright 2011 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.
 
 #include "cc/trees/tree_synchronizer.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <set>
@@ skipping 42 matching lines @@
 
 class MockLayer : public Layer {
  public:
   static scoped_refptr<MockLayer> Create(
       std::vector<int>* layer_impl_destruction_list) {
     return make_scoped_refptr(new MockLayer(layer_impl_destruction_list));
   }
 
   std::unique_ptr<LayerImpl> CreateLayerImpl(
       LayerTreeImpl* tree_impl) override {
-    return MockLayerImpl::Create(tree_impl, layer_id_);
+    return MockLayerImpl::Create(tree_impl, id());
   }
 
   void PushPropertiesTo(LayerImpl* layer_impl) override {
     Layer::PushPropertiesTo(layer_impl);
 
     MockLayerImpl* mock_layer_impl = static_cast<MockLayerImpl*>(layer_impl);
     mock_layer_impl->SetLayerImplDestructionList(layer_impl_destruction_list_);
   }
 
  private:
@@ skipping 624 matching lines @@
   host_->CommitAndCreatePendingTree();
   host_impl->ActivateSyncTree();
   EXPECT_EQ(
       CombinedAnimationScale(0.f, 0.f),
       host_impl->active_tree()->property_trees()->GetAnimationScales(
           transform_layer->transform_tree_index(), host_impl->active_tree()));
 }
 
 }  // namespace
 }  // namespace cc