cc : Don't draw animating layers which are transparent but raster them.

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 <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 354 matching lines @@
   property_trees_ = *property_trees;
   bool render_surfaces_changed =
       property_trees_.effect_tree.CreateOrReuseRenderSurfaces(
           &old_render_surfaces, this);
   if (render_surfaces_changed)
     set_needs_update_draw_properties();
   property_trees->effect_tree.PushCopyRequestsTo(&property_trees_.effect_tree);
   property_trees_.is_main_thread = false;
   property_trees_.is_active = IsActiveTree();
   property_trees_.transform_tree.set_source_to_parent_updates_allowed(false);
-  // The value of some effect node properties (like is_drawn) depends on
-  // whether we are on the active tree or not. So, we need to update the
-  // effect tree.
-  if (IsActiveTree())
-    property_trees_.effect_tree.set_needs_update(true);
 }
 
 void LayerTreeImpl::PushPropertiesTo(LayerTreeImpl* target_tree) {
   // The request queue should have been processed and does not require a push.
   DCHECK_EQ(ui_resource_request_queue_.size(), 0u);
 
   // To maintain the current scrolling node we need to use element ids which
   // are stable across the property tree update in SetPropertyTrees.
   ElementId scrolling_element_id;
   if (ScrollNode* scrolling_node = target_tree->CurrentlyScrollingNode())
@@ skipping 1707 matching lines @@
 
 void LayerTreeImpl::ResetAllChangeTracking() {
   layers_that_should_push_properties_.clear();
   // Iterate over all layers, including masks.
   for (auto& layer : *layers_)
     layer->ResetChangeTracking();
   property_trees_.ResetAllChangeTracking();
 }
 
 }  // namespace cc