Keeping track of descendants that draw content instead of recalcualting

cc/trees/damage_tracker_unittest.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/damage_tracker.h"
 
 #include "cc/base/math_util.h"
 #include "cc/layers/layer_impl.h"
 #include "cc/output/filter_operation.h"
 #include "cc/output/filter_operations.h"
@@ skipping 12 matching lines @@
 namespace {
 
 void ExecuteCalculateDrawProperties(LayerImpl* root,
                                     LayerImplList* render_surface_layer_list) {
   // Sanity check: The test itself should create the root layer's render
   //               surface, so that the surface (and its damage tracker) can
   //               persist across multiple calls to this function.
   ASSERT_TRUE(root->render_surface());
   ASSERT_FALSE(render_surface_layer_list->size());
 
+  FakeLayerTreeHostImpl::RecursiveUpdateNumChildren(root);
   LayerTreeHostCommon::CalcDrawPropsImplInputsForTesting inputs(
       root, root->bounds(), render_surface_layer_list);
   LayerTreeHostCommon::CalculateDrawProperties(&inputs);
 }
 
 void ClearDamageForAllSurfaces(LayerImpl* layer) {
   if (layer->render_surface())
     layer->render_surface()->damage_tracker()->DidDrawDamagedArea();
 
   // Recursively clear damage for any existing surface.
@@ skipping 1418 matching lines @@
     gfx::Rect root_damage_rect =
         root->render_surface()->damage_tracker()->current_damage_rect();
     gfx::Rect damage_we_care_about = gfx::Rect(i, i);
     EXPECT_LE(damage_we_care_about.right(), root_damage_rect.right());
     EXPECT_LE(damage_we_care_about.bottom(), root_damage_rect.bottom());
   }
 }
 
 }  // namespace
 }  // namespace cc