Add fixed raster scale use counter histograms.

cc/layers/layer.h

Index: cc/layers/layer.h
diff --git a/cc/layers/layer.h b/cc/layers/layer.h
index 97e83c339b461fbb9523b05e55835b552d39877a..c1ae6d3a44deda90cfe8af7b36b0674ea81e5053 100644
--- a/cc/layers/layer.h
+++ b/cc/layers/layer.h
@@ -507,6 +507,11 @@ class CC_EXPORT Layer : public base::RefCounted<Layer> {
   void OnTransformIsPotentiallyAnimatingChanged(bool is_animating);
   bool HasActiveAnimationForTesting() const;
 
+  void SetHasWillChangeTransformHint(bool has_will_change);
+  bool has_will_change_transform_hint() const {
+    return has_will_change_transform_hint_;
+  }
+
  protected:
   friend class LayerImpl;
   friend class TreeSynchronizer;
@@ -643,6 +648,7 @@ class CC_EXPORT Layer : public base::RefCounted<Layer> {
   bool force_render_surface_for_testing_ : 1;
   bool has_render_surface_ : 1;
   bool subtree_property_changed_ : 1;
+  bool has_will_change_transform_hint_ : 1;
   Region non_fast_scrollable_region_;
   Region touch_event_handler_region_;
   gfx::PointF position_;