Shared Raster Worker Threads

cc/resources/picture_pile.cc

Index: cc/resources/picture_pile.cc
diff --git a/cc/resources/picture_pile.cc b/cc/resources/picture_pile.cc
index 68d75d7aea14e29e21c65a16e6ae7eac90f17b29..951133713795d7e3aec54ccb36bf006f61a5d0f6 100644
--- a/cc/resources/picture_pile.cc
+++ b/cc/resources/picture_pile.cc
@@ -9,6 +9,7 @@
 #include <vector>
 
 #include "cc/base/region.h"
+#include "cc/base/switches.h"
 #include "cc/debug/rendering_stats_instrumentation.h"
 #include "cc/resources/picture_pile_impl.h"
 #include "cc/resources/tile_priority.h"
@@ -231,10 +232,11 @@ bool PicturePile::Update(
       }
       int recorded_pixel_count =
           picture->LayerRect().width() * picture->LayerRect().height();
+      size_t num_raster_threads = switches::GetNumRasterThreads();
       stats_instrumentation->AddRecord(best_duration, recorded_pixel_count);
-      if (num_raster_threads_ > 1)
+      if (num_raster_threads > 1)
         picture->GatherPixelRefs(tile_grid_info_);
-      picture->CloneForDrawing(num_raster_threads_);
+      picture->CloneForDrawing(static_cast<int>(num_raster_threads));
     }
 
     for (TilingData::Iterator it(&tiling_, record_rect);