Make tile size a function of the device scale factor.

cc/trees/layer_tree_settings.cc

Index: cc/trees/layer_tree_settings.cc
diff --git a/cc/trees/layer_tree_settings.cc b/cc/trees/layer_tree_settings.cc
index af0a353866180657e5e63503b863fe98b6049c84..2df65ec11dcc686419cb5d103f11662cd2bc51a5 100644
--- a/cc/trees/layer_tree_settings.cc
+++ b/cc/trees/layer_tree_settings.cc
@@ -47,9 +47,7 @@ LayerTreeSettingsScrollbarAnimatorFromProto(
 }  // namespace
 
 LayerTreeSettings::LayerTreeSettings()
-    : default_tile_size(gfx::Size(256, 256)),
-      max_untiled_layer_size(gfx::Size(512, 512)),
-      minimum_occlusion_tracking_size(gfx::Size(160, 160)),
+    : minimum_occlusion_tracking_size(gfx::Size(160, 160)),
       use_image_texture_targets(
           static_cast<size_t>(gfx::BufferFormat::LAST) + 1,
           GL_TEXTURE_2D),
@@ -94,8 +92,7 @@ bool LayerTreeSettings::operator==(const LayerTreeSettings& other) const {
          top_controls_show_threshold == other.top_controls_show_threshold &&
          top_controls_hide_threshold == other.top_controls_hide_threshold &&
          background_animation_rate == other.background_animation_rate &&
-         default_tile_size == other.default_tile_size &&
-         max_untiled_layer_size == other.max_untiled_layer_size &&
+         use_viewport_for_tile_size == other.use_viewport_for_tile_size &&
          minimum_occlusion_tracking_size ==
              other.minimum_occlusion_tracking_size &&
          tiling_interest_area_padding == other.tiling_interest_area_padding &&
@@ -156,8 +153,7 @@ void LayerTreeSettings::ToProtobuf(proto::LayerTreeSettings* proto) const {
   proto->set_top_controls_show_threshold(top_controls_show_threshold);
   proto->set_top_controls_hide_threshold(top_controls_hide_threshold);
   proto->set_background_animation_rate(background_animation_rate);
-  SizeToProto(default_tile_size, proto->mutable_default_tile_size());
-  SizeToProto(max_untiled_layer_size, proto->mutable_max_untiled_layer_size());
+  proto->set_use_viewport_for_tile_size(use_viewport_for_tile_size);
   SizeToProto(minimum_occlusion_tracking_size,
               proto->mutable_minimum_occlusion_tracking_size());
   proto->set_tiling_interest_area_padding(tiling_interest_area_padding);
@@ -217,8 +213,7 @@ void LayerTreeSettings::FromProtobuf(const proto::LayerTreeSettings& proto) {
   top_controls_show_threshold = proto.top_controls_show_threshold();
   top_controls_hide_threshold = proto.top_controls_hide_threshold();
   background_animation_rate = proto.background_animation_rate();
-  default_tile_size = ProtoToSize(proto.default_tile_size());
-  max_untiled_layer_size = ProtoToSize(proto.max_untiled_layer_size());
+  use_viewport_for_tile_size = proto.use_viewport_for_tile_size();
   minimum_occlusion_tracking_size =
       ProtoToSize(proto.minimum_occlusion_tracking_size());
   tiling_interest_area_padding = proto.tiling_interest_area_padding();