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 543 matching lines @@
     bool resourceless_software_draw = (layer_tree_host_impl_->GetDrawMode() ==
                                        DRAW_MODE_RESOURCELESS_SOFTWARE);
 
     // LayerIterator is used here instead of CallFunctionForSubtree to only
     // UpdateTilePriorities on layers that will be visible (and thus have valid
     // draw properties) and not because any ordering is required.
     typedef LayerIterator<LayerImpl> LayerIteratorType;
     LayerIteratorType end = LayerIteratorType::End(&render_surface_layer_list_);
     size_t layers_updated_count = 0;
     bool tile_priorities_updated = false;
+    if (!resourceless_software_draw) {
+      viewport_rect_for_tile_priority_ =
+          layer_tree_host_impl_->ViewportRectForTilePriority();

[boliu, 2015/01/15 01:36:05]

I guess this is ok now, but probably safer to move this above the
CalculateDrawProperties? There is no need to check resourceless_software_draw,
this is valid even inside a software draw.

[hush (inactive), 2015/01/15 01:51:59]

Yes. Done.

+    }
+
     for (LayerIteratorType it =
              LayerIteratorType::Begin(&render_surface_layer_list_);
          it != end;
          ++it) {
       if (occlusion_tracker)
         occlusion_tracker->EnterLayer(it);
 
       LayerImpl* layer = *it;
       const Occlusion& occlusion_in_content_space =
           occlusion_tracker ? occlusion_tracker->GetCurrentOcclusionForLayer(
@@ skipping 237 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