cc: Give non-drawing layers that are rasterized a lower priority.

cc/tiles/tiling_set_raster_queue_all.h

Index: cc/tiles/tiling_set_raster_queue_all.h
diff --git a/cc/tiles/tiling_set_raster_queue_all.h b/cc/tiles/tiling_set_raster_queue_all.h
index 73bb4c9e17b24c21988e1b4a8985818646437470..392f281103bac4afadf17a58adfe95f26c80b8ae 100644
--- a/cc/tiles/tiling_set_raster_queue_all.h
+++ b/cc/tiles/tiling_set_raster_queue_all.h
@@ -22,12 +22,14 @@ namespace cc {
 class CC_EXPORT TilingSetRasterQueueAll {
  public:
   TilingSetRasterQueueAll(PictureLayerTilingSet* tiling_set,
-                          bool prioritize_low_res);
+                          bool prioritize_low_res,
+                          bool is_non_drawing_layer);
   ~TilingSetRasterQueueAll();
 
   const PrioritizedTile& Top() const;
   void Pop();
   bool IsEmpty() const;
+  bool is_non_drawing_layer() const { return is_non_drawing_layer_; }
 
  private:
   // Helper base class for individual region iterators.
@@ -190,6 +192,7 @@ class CC_EXPORT TilingSetRasterQueueAll {
   // ideal pending high res.
   base::StackVector<IterationStage, 6> stages_;
   TilingIterator iterators_[NUM_ITERATORS];
+  bool is_non_drawing_layer_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(TilingSetRasterQueueAll);
 };