Cache viewport rect for tile priority in UpdateTiles

cc/trees/layer_tree_impl.cc

Index: cc/trees/layer_tree_impl.cc
diff --git a/cc/trees/layer_tree_impl.cc b/cc/trees/layer_tree_impl.cc
index 041c5fea5186105c11c86371cea45ed66c3ee206..df27d089132091f63c0bcfbedd3aefb8fca262aa 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -511,6 +511,8 @@ bool LayerTreeImpl::UpdateDrawProperties() {
   needs_update_draw_properties_ = false;
   render_surface_layer_list_.clear();
 
+  viewport_rect_for_tile_priority_ =
+      layer_tree_host_impl_->ViewportRectForTilePriority();

[danakj, 2015/01/20 22:42:46]

I find it awkward that LTI mirrors the LTHI method name, but it's a cached value
instead of just calling through to the LTHI like other methods in LTI do.

[hush (inactive), 2015/01/21 00:43:07]

good point... it is inconsistent..
I will cache it in PictureLayerImpl when updateTiles is called.

   {
     TRACE_EVENT2("cc",
                  "LayerTreeImpl::UpdateDrawProperties",
@@ -818,7 +820,7 @@ gfx::Size LayerTreeImpl::DrawViewportSize() const {
 }
 
 const gfx::Rect LayerTreeImpl::ViewportRectForTilePriority() const {
-  return layer_tree_host_impl_->ViewportRectForTilePriority();
+  return viewport_rect_for_tile_priority_;
 }
 
 scoped_ptr<ScrollbarAnimationController>