cc: Add threaded GPU rasterization.

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 <cmath>
 #include <limits>
 #include <set>
@@ skipping 1118 matching lines @@
 }
 
 float PictureLayerImpl::MaximumTilingContentsScale() const {
   float max_contents_scale = tilings_->GetMaximumContentsScale();
   return std::max(max_contents_scale, MinimumContentsScale());
 }
 
 scoped_ptr<PictureLayerTilingSet>
 PictureLayerImpl::CreatePictureLayerTilingSet() {
   const LayerTreeSettings& settings = layer_tree_impl()->settings();
+  float skewport_factor = layer_tree_impl()->use_gpu_rasterization()
+                              ? settings.gpu_rasterization_skewport_factor
+                              : 1.0f;
   return PictureLayerTilingSet::Create(
       this, settings.max_tiles_for_interest_area,
-      layer_tree_impl()->use_gpu_rasterization()
-          ? 0.f
-          : settings.skewport_target_time_in_seconds,
+      settings.skewport_target_time_in_seconds * skewport_factor,
       settings.skewport_extrapolation_limit_in_content_pixels);
 }
 
 void PictureLayerImpl::UpdateIdealScales() {
   DCHECK(CanHaveTilings());
 
   float min_contents_scale = MinimumContentsScale();
   DCHECK_GT(min_contents_scale, 0.f);
   float min_page_scale = layer_tree_impl()->min_page_scale_factor();
   DCHECK_GT(min_page_scale, 0.f);
@@ skipping 79 matching lines @@
 
 bool PictureLayerImpl::IsOnActiveOrPendingTree() const {
   return !layer_tree_impl()->IsRecycleTree();
 }
 
 bool PictureLayerImpl::HasValidTilePriorities() const {
   return IsOnActiveOrPendingTree() && IsDrawnRenderSurfaceLayerListMember();
 }
 
 }  // namespace cc