Make ui::Layer use the cc:LayerTreeHost scale factor directly

ui/aura/window_unittest.cc

 // Copyright (c) 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 "ui/aura/window.h"
 
 #include <string>
 #include <utility>
 #include <vector>
 
@@ skipping 1887 matching lines @@
 // Make sure that properties which should persist from the old layer to the new
 // layer actually do.
 TEST_F(WindowTest, RecreateLayer) {
   // Set properties to non default values.
   Window w(new ColorTestWindowDelegate(SK_ColorWHITE));
   w.set_id(1);
   w.Init(aura::WINDOW_LAYER_SOLID_COLOR);
   w.SetBounds(gfx::Rect(0, 0, 100, 100));
 
   ui::Layer* layer = w.layer();
-  layer->set_scale_content(false);
   layer->SetVisible(false);
   layer->SetMasksToBounds(true);
 
   ui::Layer child_layer;
   layer->Add(&child_layer);
 
   scoped_ptr<ui::Layer> old_layer(w.RecreateLayer());
   layer = w.layer();
   EXPECT_EQ(ui::LAYER_SOLID_COLOR, layer->type());
-  EXPECT_FALSE(layer->scale_content());
   EXPECT_FALSE(layer->visible());
   EXPECT_EQ(1u, layer->children().size());
   EXPECT_TRUE(layer->GetMasksToBounds());
   EXPECT_EQ("0,0 100x100", w.bounds().ToString());
   EXPECT_EQ("0,0 100x100", layer->bounds().ToString());
 }
 
 // Verify that RecreateLayer() stacks the old layer above the newly creatd
 // layer.
 TEST_F(WindowTest, RecreateLayerZOrder) {
@@ skipping 1415 matching lines @@
               BuildRootLayerTreeDescription(*root.layer()))
         << "layer tree doesn't match at " << i;
     EXPECT_EQ(data[i].expected_description,
               BuildRootWindowTreeDescription(root))
         << "window tree doesn't match at " << i;
   }
 }
 
 }  // namespace test
 }  // namespace aura