cc: Move gpu rasterization flag from LayerImpl to LayerTreeImpl.

cc/layers/picture_layer_impl.h

Index: cc/layers/picture_layer_impl.h
diff --git a/cc/layers/picture_layer_impl.h b/cc/layers/picture_layer_impl.h
index b559e3d491af7ae4246907b22d6487759cc388bb..80d09dde721ad2e533c11d819f4241e986c6327c 100644
--- a/cc/layers/picture_layer_impl.h
+++ b/cc/layers/picture_layer_impl.h
@@ -14,6 +14,7 @@
 #include "cc/resources/picture_layer_tiling.h"
 #include "cc/resources/picture_layer_tiling_set.h"
 #include "cc/resources/picture_pile_impl.h"
+#include "cc/trees/layer_tree_impl.h"
 #include "skia/ext/refptr.h"
 #include "third_party/skia/include/core/SkPicture.h"
 
@@ -131,8 +132,9 @@ class CC_EXPORT PictureLayerImpl
 
   virtual void RunMicroBenchmark(MicroBenchmarkImpl* benchmark) OVERRIDE;
 
-  void SetUseGpuRasterization(bool use_gpu);
-  bool ShouldUseGpuRasterization() const { return use_gpu_rasterization_; }
+  bool use_gpu_rasterization() const {
+    return layer_tree_impl()->use_gpu_rasterization();
+  }
 
   // Functions used by tile manager.
   void DidUnregisterLayer();
@@ -151,7 +153,7 @@ class CC_EXPORT PictureLayerImpl
   void ManageTilings(bool animating_transform_to_screen,
                      float maximum_animation_contents_scale);
   bool ShouldHaveLowResTiling() const {
-    return should_use_low_res_tiling_ && !ShouldUseGpuRasterization();
+    return should_use_low_res_tiling_ && !use_gpu_rasterization();
   }
   virtual bool ShouldAdjustRasterScale(
       bool animating_transform_to_screen) const;
@@ -212,7 +214,6 @@ class CC_EXPORT PictureLayerImpl
   // after a CalculateContentsScale/ManageTilings.
   bool should_update_tile_priorities_;
   bool should_use_low_res_tiling_;
-  bool use_gpu_rasterization_;
 
   bool layer_needs_to_register_itself_;