Make FadingEdgeScrollView more generic

chrome/android/java/res/values/dimens.xml

 <?xml version="1.0" encoding="utf-8"?>
 <!-- Copyright 2014 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. -->
 
 <resources>
     <!-- Connection info popup dimensions -->
     <dimen name="connection_info_padding_wide">24dp</dimen>
     <dimen name="connection_info_padding_thin">16dp</dimen>
 
@@ skipping 387 matching lines @@
     <dimen name="pref_autofill_field_bottom_margin">8dp</dimen>
     <!-- The dropdown element has no embedded bottom padding like the TextView has so the margin
          is doubled. -->
     <dimen name="pref_autofill_dropdown_bottom_margin">16dp</dimen>
     <dimen name="pref_autofill_touch_target_padding">15dp</dimen>
     <dimen name="pref_child_account_reduced_padding">4dp</dimen>
 
     <!-- Dialog dimensions.
          https://www.google.com/design/spec/components/dialogs.html#dialogs-simple-dialogs -->
     <dimen name="dialog_width_unit">56dp</dimen>  <!-- MD dialog widths are multiples of this. -->
+    <dimen name="separator_height">1dp</dimen>
 
     <!-- Downloads dimensions. -->
     <dimen name="downloads_item_icon_size">48dp</dimen>
     <!-- file type icon size = downloads_item_icon_size - 2 * padding -->
     <dimen name="downloads_item_file_type_icon_padding">12dp</dimen>
     <dimen name="downloads_item_margin">16dp</dimen>
 
     <!-- SelectableListLayout dimensions -->
     <dimen name="selectable_list_layout_end_icon">24dp</dimen>
     <dimen name="selectable_list_layout_row_end_padding">16dp</dimen>
     <dimen name="selectable_list_layout_start_icon_width">56dp</dimen>
     <dimen name="toolbar_wide_display_nav_icon_offset">-18dp</dimen>
     <dimen name="toolbar_wide_display_end_offset">-14dp</dimen>
 
     <!-- Bottom sheet bottom nav dimensions -->
     <dimen name="bottom_nav_height">56dp</dimen>
     <dimen name="bottom_nav_space_from_toolbar">96dp</dimen>
     <!-- The following two dimensions override defaults in Android's BottomNavigationView -->
     <dimen name="design_bottom_navigation_text_size">12sp</dimen>
     <dimen name="design_bottom_navigation_active_text_size">14sp</dimen>
 
     <!--  Miscellaneous dimensions -->
     <dimen name="action_bar_shadow_height">10dp</dimen>
     <dimen name="card_corner_radius">2dp</dimen>
     <dimen name="list_item_corner_radius">3dp</dimen>
     <dimen name="list_item_lateral_padding">1dp</dimen>
     <dimen name="history_default_text_margin">16dp</dimen>
 </resources>