Add fixed raster scale use counter histograms.

cc/trees/layer_tree_host.h

Index: cc/trees/layer_tree_host.h
diff --git a/cc/trees/layer_tree_host.h b/cc/trees/layer_tree_host.h
index 63208b4e578c46ffa5a38107a9c5cfdb7cb290a3..6bdab129a9e68acede02e98a65af47f82bfb1afa 100644
--- a/cc/trees/layer_tree_host.h
+++ b/cc/trees/layer_tree_host.h
@@ -419,6 +419,10 @@ class CC_EXPORT LayerTreeHost : public MutatorHostClient {
     return image_serialization_processor_;
   }
 
+  void ReportFixedRasterScaleUseCounters(
+      bool has_fixed_raster_scale_blurry_content,
+      bool has_fixed_raster_scale_potential_performance_regression);
+
  protected:
   LayerTreeHost(InitParams* params, CompositorMode mode);
   void InitializeThreaded(
@@ -587,6 +591,9 @@ class CC_EXPORT LayerTreeHost : public MutatorHostClient {
   uint32_t surface_id_namespace_;
   uint32_t next_surface_sequence_;
 
+  bool has_fixed_raster_scale_blurry_content_;
+  bool has_fixed_raster_scale_potential_performance_regression_;
+
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHost);
 };