Update from https://crrev.com/303153

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 488 matching lines @@
         resource_provider()->max_texture_size(),
         settings().can_use_lcd_text,
         can_render_to_separate_surface,
         settings().layer_transforms_should_scale_layer_contents,
         &render_surface_layer_list_,
         render_surface_layer_list_id_);
     LayerTreeHostCommon::CalculateDrawProperties(&inputs);
   }
 
   {
-    TRACE_EVENT2("cc",
-                 "LayerTreeImpl::UpdateTilePriorities",
-                 "IsActive",
-                 IsActiveTree(),
-                 "SourceFrameNumber",
-                 source_frame_number_);
+    TRACE_EVENT_BEGIN2("cc", "LayerTreeImpl::UpdateTilePriorities", "IsActive",
+                       IsActiveTree(), "SourceFrameNumber",
+                       source_frame_number_);
     scoped_ptr<OcclusionTracker<LayerImpl>> occlusion_tracker;
     if (settings().use_occlusion_for_tile_prioritization) {
       occlusion_tracker.reset(new OcclusionTracker<LayerImpl>(
           root_layer()->render_surface()->content_rect()));
       occlusion_tracker->set_minimum_tracking_size(
           settings().minimum_occlusion_tracking_size);
     }
 
     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;
     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(
                                   layer->draw_transform())
                             : Occlusion();
 
       if (it.represents_itself()) {
         layer->UpdateTiles(occlusion_in_content_space,
                            resourceless_software_draw);
+        ++layers_updated_count;
       }
 
       if (!it.represents_contributing_render_surface()) {
         if (occlusion_tracker)
           occlusion_tracker->LeaveLayer(it);
         continue;
       }
 
       if (layer->mask_layer()) {
         layer->mask_layer()->UpdateTiles(occlusion_in_content_space,
                                          resourceless_software_draw);
+        ++layers_updated_count;
       }
       if (layer->replica_layer() && layer->replica_layer()->mask_layer()) {
         layer->replica_layer()->mask_layer()->UpdateTiles(
             occlusion_in_content_space, resourceless_software_draw);
+        ++layers_updated_count;
       }
 
       if (occlusion_tracker)
         occlusion_tracker->LeaveLayer(it);
     }
+
+    TRACE_EVENT_END1("cc", "LayerTreeImpl::UpdateTilePriorities",
+                     "layers_updated_count", layers_updated_count);
   }
 
   DCHECK(!needs_update_draw_properties_) <<
       "CalcDrawProperties should not set_needs_update_draw_properties()";
   return true;
 }
 
 const LayerImplList& LayerTreeImpl::RenderSurfaceLayerList() const {
   // If this assert triggers, then the list is dirty.
   DCHECK(!needs_update_draw_properties_);
@@ skipping 938 matching lines @@
                                   page_scale,
                                   duration.InSecondsF());
   }
 }
 
 scoped_ptr<PageScaleAnimation> LayerTreeImpl::TakePageScaleAnimation() {
   return page_scale_animation_.Pass();
 }
 
 }  // namespace cc