Revert "cc: Remove layers that are not drawn from tile manager."

cc/layers/picture_layer_impl.cc

 // Copyright 2012 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/layers/picture_layer_impl.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/time/time.h"
@@ skipping 341 matching lines @@
   }
 
   // Aggressively remove any tilings that are not seen to save memory. Note
   // that this is at the expense of doing cause more frequent re-painting. A
   // better scheme would be to maintain a tighter visible_content_rect for the
   // finer tilings.
   CleanUpTilingsOnActiveLayer(seen_tilings);
 }
 
 void PictureLayerImpl::DidUnregisterLayer() {
-  TRACE_EVENT0("cc", "PictureLayerImpl::DidUnregisterLayer");
-
   layer_needs_to_register_itself_ = true;
-  RemoveAllTilings();
 }
 
 void PictureLayerImpl::UpdateTilePriorities() {
-  TRACE_EVENT0("cc", "PictureLayerImpl::UpdateTilePriorities");
-
-  DCHECK(IsDrawnRenderSurfaceLayerListMember());
   DCHECK(!needs_post_commit_initialization_);
   CHECK(should_update_tile_priorities_);
 
   if (layer_needs_to_register_itself_) {
     layer_tree_impl()->tile_manager()->RegisterPictureLayerImpl(this);
     layer_needs_to_register_itself_ = false;
   }
 
   if (layer_tree_impl()->device_viewport_valid_for_tile_management()) {
     visible_rect_for_tile_priority_ = visible_content_rect();
@@ skipping 1181 matching lines @@
   return iterator_index_ < iterators_.size();
 }
 
 bool PictureLayerImpl::LayerEvictionTileIterator::IsCorrectType(
     PictureLayerTiling::TilingEvictionTileIterator* it) const {
   return it->get_type() == iteration_stage_ &&
          (**it)->required_for_activation() == required_for_activation_;
 }
 
 }  // namespace cc