Use the solid color detection to create solid layers

cc/trees/layer_tree_host_unittest_scroll.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/trees/layer_tree_host.h"
 
 #include "base/memory/weak_ptr.h"
 #include "cc/layers/layer.h"
 #include "cc/layers/layer_impl.h"
 #include "cc/layers/picture_layer.h"
@@ skipping 548 matching lines @@
       expected_no_scroll_layer_impl = root_scroll_layer_impl;
     } else {
       expected_scroll_layer_impl = root_scroll_layer_impl;
       expected_no_scroll_layer_impl = child_layer_impl;
     }
 
     EXPECT_VECTOR_EQ(gfx::Vector2d(), root_impl->ScrollDelta());
     EXPECT_VECTOR_EQ(gfx::Vector2d(),
                      expected_no_scroll_layer_impl->ScrollDelta());
 
-    // Ensure device scale factor is affecting the layers.
-    EXPECT_FLOAT_EQ(device_scale_factor_,
-                    root_scroll_layer_impl->HighResTiling()->contents_scale());
-
-    EXPECT_FLOAT_EQ(device_scale_factor_,
-                    child_layer_impl->HighResTiling()->contents_scale());
-
+    // Ensure device scale factor matches the active tree.
+    EXPECT_EQ(device_scale_factor_, impl->active_tree()->device_scale_factor());
     switch (impl->active_tree()->source_frame_number()) {
       case 0: {
         // Gesture scroll on impl thread.
         InputHandler::ScrollStatus status = impl->ScrollBegin(
             gfx::ToCeiledPoint(expected_scroll_layer_impl->position() -
                                gfx::Vector2dF(0.5f, 0.5f)),
             InputHandler::Gesture);
         EXPECT_EQ(InputHandler::ScrollStarted, status);
         impl->ScrollBy(gfx::Point(), scroll_amount_);
         impl->ScrollEnd();
@@ skipping 634 matching lines @@
   RunTest(true, false, true);
 }
 
 TEST_F(LayerTreeHostScrollTestLayerStructureChange, ScrollDestroyWholeTree) {
   scroll_destroy_whole_tree_ = true;
   RunTest(true, false, true);
 }
 
 }  // namespace
 }  // namespace cc