cc: Report only on active tiles in tracing.

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 808 matching lines @@
 }
 
 DebugRectHistory* LayerTreeImpl::debug_rect_history() const {
   return layer_tree_host_impl_->debug_rect_history();
 }
 
 AnimationRegistrar* LayerTreeImpl::animationRegistrar() const {
   return layer_tree_host_impl_->animation_registrar();
 }
 
+void LayerTreeImpl::AllTilesForTracingInto(std::set<const Tile*>* tiles) const {
+  typedef LayerIterator<LayerImpl> LayerIteratorType;
+  LayerIteratorType end = LayerIteratorType::End(&render_surface_layer_list_);
+  for (LayerIteratorType it =
+           LayerIteratorType::Begin(&render_surface_layer_list_);
+       it != end;
+       ++it) {
+    if (!it.represents_itself())
+      continue;
+    LayerImpl* layer_impl = *it;
+    layer_impl->AllTilesForTracingInto(tiles);
+  }
+}
+
 void LayerTreeImpl::AsValueInto(base::debug::TracedValue* state) const {
   TracedValue::MakeDictIntoImplicitSnapshot(state, "cc::LayerTreeImpl", this);
 
   state->BeginDictionary("root_layer");
   root_layer_->AsValueInto(state);
   state->EndDictionary();
 
   state->BeginArray("render_surface_layer_list");
   typedef LayerIterator<LayerImpl> LayerIteratorType;
   LayerIteratorType end = LayerIteratorType::End(&render_surface_layer_list_);
@@ skipping 557 matching lines @@
 
 void LayerTreeImpl::UnregisterPictureLayerImpl(PictureLayerImpl* layer) {
   layer_tree_host_impl_->UnregisterPictureLayerImpl(layer);
 }
 
 void LayerTreeImpl::InputScrollAnimationFinished() {
   layer_tree_host_impl_->ScrollEnd();
 }
 
 }  // namespace cc