cc: Use ScreenSpaceTransform to determine content scale

cc/test/layer_tree_host_common_test.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/test/layer_tree_host_common_test.h"
 
 #include <stddef.h>
 
 #include "cc/layers/layer.h"
 #include "cc/layers/layer_impl.h"
@@ skipping 160 matching lines @@
 
 void LayerTreeHostCommonTestBase::ExecuteCalculateDrawProperties(
     LayerImpl* root_layer,
     float device_scale_factor,
     float page_scale_factor,
     LayerImpl* page_scale_layer,
     bool can_use_lcd_text,
     bool layers_always_allowed_lcd_text) {
   root_layer->layer_tree_impl()->SetDeviceScaleFactor(device_scale_factor);
 
+  EXPECT_TRUE(page_scale_layer || (page_scale_factor == 1.f));
+
   gfx::Transform identity_matrix;
   gfx::Size device_viewport_size =
       gfx::Size(root_layer->bounds().width() * device_scale_factor,
                 root_layer->bounds().height() * device_scale_factor);
 
   render_surface_layer_list_impl_.reset(new LayerImplList);
 
   // We are probably not testing what is intended if the root_layer bounds are
   // empty.
   DCHECK(!root_layer->bounds().IsEmpty());
@@ skipping 36 matching lines @@
 
 LayerTreeHostCommonTest::LayerTreeHostCommonTest()
     : LayerTreeHostCommonTestBase(LayerTreeSettings()) {}
 
 LayerTreeHostCommonTest::LayerTreeHostCommonTest(
     const LayerTreeSettings& settings)
     : LayerTreeHostCommonTestBase(settings) {
 }
 
 }  // namespace cc