cc: Use multiple PrepareTiles approaches

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 <algorithm>
 #include <limits>
 #include <set>
 
@@ skipping 717 matching lines @@
   if (next_activation_forces_redraw_) {
     layer_tree_host_impl_->SetFullRootLayerDamage();
     next_activation_forces_redraw_ = false;
   }
 
   if (scrolling_layer_id_from_previous_tree_) {
     currently_scrolling_layer_ = LayerTreeHostCommon::FindLayerInSubtree(
         root_layer(), scrolling_layer_id_from_previous_tree_);
   }
 
-  // Always reset this flag on activation, as we would only have activated
-  // if we were in a good state.
-  layer_tree_host_impl_->ResetRequiresHighResToDraw();
-
   if (root_layer()) {
     LayerTreeHostCommon::CallFunctionForSubtree(
         root_layer(), [](LayerImpl* layer) { layer->DidBecomeActive(); });
   }
 
   devtools_instrumentation::DidActivateLayerTree(layer_tree_host_impl_->id(),
                                                  source_frame_number_);
 }
 
 bool LayerTreeImpl::ContentsTexturesPurged() const {
@@ skipping 813 matching lines @@
     scoped_ptr<PendingPageScaleAnimation> pending_animation) {
   pending_page_scale_animation_ = pending_animation.Pass();
 }
 
 scoped_ptr<PendingPageScaleAnimation>
     LayerTreeImpl::TakePendingPageScaleAnimation() {
   return pending_page_scale_animation_.Pass();
 }
 
 }  // namespace cc