cc: Make LayerTreeHost a protected Layer member.

cc/layers/nine_patch_layer_unittest.cc

 // Copyright 2012 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/layers/nine_patch_layer.h"
 
 #include "cc/resources/resource_provider.h"
 #include "cc/resources/scoped_ui_resource.h"
 #include "cc/test/fake_layer_tree_host.h"
 #include "cc/test/fake_layer_tree_host_client.h"
@@ skipping 32 matching lines @@
 };
 
 TEST_F(NinePatchLayerTest, SetLayerProperties) {
   scoped_refptr<NinePatchLayer> test_layer = NinePatchLayer::Create();
   ASSERT_TRUE(test_layer.get());
   test_layer->SetIsDrawable(true);
   test_layer->SetBounds(gfx::Size(100, 100));
 
   layer_tree_host_->SetRootLayer(test_layer);
   Mock::VerifyAndClearExpectations(layer_tree_host_.get());
-  EXPECT_EQ(test_layer->layer_tree_host(), layer_tree_host_.get());
+  EXPECT_EQ(test_layer->GetLayerTreeHostForTesting(), layer_tree_host_.get());
 
   gfx::Rect screen_space_clip_rect;
   test_layer->SavePaintProperties();
   test_layer->Update();
 
   EXPECT_FALSE(test_layer->DrawsContent());
 
   bool is_opaque = false;
   std::unique_ptr<ScopedUIResource> resource =
       ScopedUIResource::Create(layer_tree_host_->GetUIResourceManager(),
                                UIResourceBitmap(gfx::Size(10, 10), is_opaque));
   gfx::Rect aperture(5, 5, 1, 1);
   bool fill_center = true;
   test_layer->SetAperture(aperture);
   test_layer->SetUIResourceId(resource->id());
   test_layer->SetFillCenter(fill_center);
   test_layer->Update();
 
   EXPECT_TRUE(test_layer->DrawsContent());
 }
 
 }  // namespace
 }  // namespace cc