Cache viewport rect for tile priority in UpdateTiles

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 <limits>
 #include <set>
 
 #include "base/debug/trace_event.h"
@@ skipping 493 matching lines @@
   // For max_texture_size.
   if (!layer_tree_host_impl_->renderer())
     return false;
 
   if (!root_layer())
     return false;
 
   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",
                  "IsActive",
                  IsActiveTree(),
                  "SourceFrameNumber",
                  source_frame_number_);
     LayerImpl* page_scale_layer =
         page_scale_layer_ ? page_scale_layer_ : InnerViewportContainerLayer();
     bool can_render_to_separate_surface =
@@ skipping 287 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 {
-  return layer_tree_host_impl_->ViewportRectForTilePriority();
+  return viewport_rect_for_tile_priority_;
 }
 
 scoped_ptr<ScrollbarAnimationController>
 LayerTreeImpl::CreateScrollbarAnimationController(LayerImpl* scrolling_layer) {
   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(
       settings().scrollbar_fade_resize_delay_ms);
@@ skipping 691 matching lines @@
     scoped_ptr<PendingPageScaleAnimation> pending_animation) {
   pending_page_scale_animation_ = pending_animation.Pass();
 }
 
 scoped_ptr<PendingPageScaleAnimation>
     LayerTreeImpl::TakePendingPageScaleAnimation() {
   return pending_page_scale_animation_.Pass();
 }
 
 }  // namespace cc