Set default pinch viewport overlay scrollbar thickness in WebPreferences.

webkit/common/webpreferences.h

 // Copyright 2013 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.
 //
 // A struct for managing webkit's settings.
 //
 // Adding new values to this class probably involves updating
 // WebKit::WebSettings, content/common/view_messages.h, browser/tab_contents/
 // render_view_host_delegate_helper.cc, and browser/profiles/profile.cc.
 
@@ skipping 135 matching lines @@
   bool should_respect_image_orientation;
   int number_of_cpu_cores;
   webkit_glue::EditingBehavior editing_behavior;
   bool supports_multiple_windows;
   bool viewport_enabled;
   bool initialize_at_minimum_page_scale;
   bool smart_insert_delete_enabled;
   bool spatial_navigation_enabled;
   bool experimental_websocket_enabled;
   bool pinch_virtual_viewport_enabled;
+  int pinch_overlay_scrollbar_thickness;
 
   // This flags corresponds to a Page's Settings' setCookieEnabled state. It
   // only controls whether or not the "document.cookie" field is properly
   // connected to the backing store, for instance if you wanted to be able to
   // define custom getters and setters from within a unique security content
   // without raising a DOM security exception.
   bool cookie_enabled;
 
 #if defined(OS_ANDROID)
   bool text_autosizing_enabled;
   float font_scale_factor;
   bool force_enable_zoom;
   bool double_tap_to_zoom_enabled;
   bool user_gesture_required_for_media_playback;
   GURL default_video_poster_url;
   bool support_deprecated_target_density_dpi;
   bool use_wide_viewport;
 #endif
 
   // We try to keep the default values the same as the default values in
   // chrome, except for the cases where it would require lots of extra work for
   // the embedder to use the same default value.
   WebPreferences();
   ~WebPreferences();
 };
 
 #endif  // WEBKIT_COMMON_WEBPREFERENCES_H__