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..f3a14588617fdb228d2ad460a2f9cee9717aeebd 100644
--- a/cc/layers/layer.h
+++ b/cc/layers/layer.h
@@ -507,6 +507,13 @@ class CC_EXPORT Layer : public base::RefCounted<Layer> {
   void OnTransformIsPotentiallyAnimatingChanged(bool is_animating);
   bool HasActiveAnimationForTesting() const;
 
+  void set_has_will_change_transform_hint(bool has_will_change) {
+    has_will_change_transform_hint_ = has_will_change;
+  }
+  bool has_will_change_transform_hint() const {
+    return has_will_change_transform_hint_;
+  }
+
  protected:
   friend class LayerImpl;
   friend class TreeSynchronizer;
@@ -680,6 +687,8 @@ class CC_EXPORT Layer : public base::RefCounted<Layer> {
   gfx::Rect visible_layer_rect_;
   size_t num_unclipped_descendants_;
 
+  bool has_will_change_transform_hint_;
+
   DISALLOW_COPY_AND_ASSIGN(Layer);
 };