Add fixed raster scale use counter histograms.

cc/layers/picture_layer_impl.h

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_LAYERS_PICTURE_LAYER_IMPL_H_
 #define CC_LAYERS_PICTURE_LAYER_IMPL_H_
 
 #include <stddef.h>
 
 #include <map>
@@ skipping 112 matching lines @@
   PictureLayerImpl* twin_layer_;
 
   std::unique_ptr<PictureLayerTilingSet> tilings_;
   scoped_refptr<RasterSource> raster_source_;
   Region invalidation_;
 
   float ideal_page_scale_;
   float ideal_device_scale_;
   float ideal_source_scale_;
   float ideal_contents_scale_;
+  float last_ideal_source_scale_;
 
   float raster_page_scale_;
   float raster_device_scale_;
   float raster_source_scale_;
   float raster_contents_scale_;
   float low_res_raster_contents_scale_;
 
   bool raster_source_scale_is_fixed_;
   bool was_screen_space_transform_animating_;
   bool only_used_low_res_last_append_quads_;
@@ skipping 13 matching lines @@
   // of comparing pointers, since objects pointed to are not guaranteed to
   // exist.
   std::vector<PictureLayerTiling*> last_append_quads_tilings_;
 
   DISALLOW_COPY_AND_ASSIGN(PictureLayerImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_PICTURE_LAYER_IMPL_H_