cc: Make PaintedScrollbarLayer not use ContentsScalingLayer

cc/layers/painted_scrollbar_layer_impl_unittest.cc

 // Copyright 2014 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/painted_scrollbar_layer_impl.h"
 
 #include "cc/test/layer_test_common.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace cc {
@@ skipping 18 matching lines @@
   UIResourceId track_uid = 6;
   UIResourceBitmap track_bitmap(track_sk_bitmap);
   impl.host_impl()->CreateUIResource(track_uid, track_bitmap);
 
   ScrollbarOrientation orientation = VERTICAL;
 
   PaintedScrollbarLayerImpl* scrollbar_layer_impl =
       impl.AddChildToRoot<PaintedScrollbarLayerImpl>(orientation);
   scrollbar_layer_impl->SetBounds(layer_size);
   scrollbar_layer_impl->SetContentBounds(layer_size);
+  scrollbar_layer_impl->set_internal_content_scale_and_bounds(1.f, layer_size);
   scrollbar_layer_impl->SetDrawsContent(true);
   scrollbar_layer_impl->SetThumbThickness(layer_size.width());
   scrollbar_layer_impl->SetThumbLength(500);
   scrollbar_layer_impl->SetTrackLength(layer_size.height());
   scrollbar_layer_impl->SetCurrentPos(100.f / 4);
   scrollbar_layer_impl->SetMaximum(100);
   scrollbar_layer_impl->SetVisibleToTotalLengthRatio(1.f / 2);
   scrollbar_layer_impl->set_track_ui_resource_id(track_uid);
   scrollbar_layer_impl->set_thumb_ui_resource_id(thumb_uid);
 
@@ skipping 33 matching lines @@
     LayerTestCommon::VerifyQuadsAreOccluded(
         impl.quad_list(), occluded, &partially_occluded_count);
     // The layer outputs two quads, which is partially occluded.
     EXPECT_EQ(2u, impl.quad_list().size());
     EXPECT_EQ(2u, partially_occluded_count);
   }
 }
 
 }  // namespace
 }  // namespace cc