Hide pinch viewport scrollbars when near minimum scale.

cc/trees/layer_tree_settings.h

 // Copyright 2011 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_TREES_LAYER_TREE_SETTINGS_H_
 #define CC_TREES_LAYER_TREE_SETTINGS_H_
 
 #include "base/basictypes.h"
 #include "cc/base/cc_export.h"
 #include "cc/debug/layer_tree_debug_state.h"
@@ skipping 28 matching lines @@
 
   enum ScrollbarAnimator {
     NoAnimator,
     LinearFade,
     Thinning,
   };
   ScrollbarAnimator scrollbar_animator;
   int scrollbar_fade_delay_ms;
   int scrollbar_fade_resize_delay_ms;
   int scrollbar_fade_duration_ms;
+  float scrollbar_show_scale_threshold;
   SkColor solid_color_scrollbar_color;
   bool calculate_top_controls_position;
   bool timeout_and_draw_when_animation_checkerboards;
   int maximum_number_of_failed_draws_before_draw_is_forced_;
   bool layer_transforms_should_scale_layer_contents;
   bool layers_always_allowed_lcd_text;
   float minimum_contents_scale;
   float low_res_contents_scale_factor;
   float top_controls_show_threshold;
   float top_controls_hide_threshold;
@@ skipping 21 matching lines @@
   bool record_full_layer;
   bool use_display_lists;
   bool verify_property_trees;
 
   LayerTreeDebugState initial_debug_state;
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_SETTINGS_H_