Make tile size a function of the device scale factor.

cc/trees/layer_tree_impl.cc

 // Copyright 2011 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_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 1238 matching lines @@
 }
 
 gfx::Rect LayerTreeImpl::DeviceViewport() const {
   return layer_tree_host_impl_->DeviceViewport();
 }
 
 gfx::Size LayerTreeImpl::DrawViewportSize() const {
   return layer_tree_host_impl_->DrawViewportSize();
 }
 
-const gfx::Rect LayerTreeImpl::ViewportRectForTilePriority() const {
+gfx::Size LayerTreeImpl::GetStableScreenSize() const {
+  return layer_tree_host_impl_->GetStableScreenSize(this);
+}
+
+gfx::Rect LayerTreeImpl::ViewportRectForTilePriority() const {
   return layer_tree_host_impl_->ViewportRectForTilePriority();
 }
 
 std::unique_ptr<ScrollbarAnimationController>
 LayerTreeImpl::CreateScrollbarAnimationController(int scroll_layer_id) {
   DCHECK(settings().scrollbar_fade_delay_ms);
   DCHECK(settings().scrollbar_fade_duration_ms);
   base::TimeDelta delay =
       base::TimeDelta::FromMilliseconds(settings().scrollbar_fade_delay_ms);
   base::TimeDelta resize_delay = base::TimeDelta::FromMilliseconds(
@@ skipping 817 matching lines @@
 
 void LayerTreeImpl::ResetAllChangeTracking() {
   layers_that_should_push_properties_.clear();
   // Iterate over all layers, including masks and replicas.
   for (auto& layer : *layers_)
     layer->ResetChangeTracking();
   property_trees_.ResetAllChangeTracking();
 }
 
 }  // namespace cc