[NTP::Downloads] Store file type icon padding as a constant.

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 287 matching lines @@
     <dimen name="ntp_search_box_height">62dp</dimen>
     <dimen name="ntp_search_box_shadow_width">4dp</dimen>
     <dimen name="ntp_search_box_transition_length">16dp</dimen>
     <dimen name="ntp_wide_card_lateral_margins">48dp</dimen>
     <dimen name="ntp_list_item_min_height">48dp</dimen>
     <dimen name="ntp_list_item_text_size">16sp</dimen>
     <dimen name="ntp_shadow_height">9dp</dimen>
     <dimen name="ntp_sign_in_promo_margin_top">20dp</dimen>
     <dimen name="ntp_progress_indicator_diameter">56dp</dimen>
     <dimen name="snippets_thumbnail_size">72dp</dimen>
+    <!-- file type icon size = snippets_thumbnail_size - 2 * padding -->
+    <dimen name="snippets_thumbnail_file_type_icon_padding">20dp</dimen>
     <dimen name="snippets_thumbnail_margin">16dp</dimen>
     <!-- The default padding for the peeking card and the amount the card peeks by in the current
          peeking card animation (the calculations assume this is the same). -->
     <dimen name="snippets_padding">16dp</dimen>
     <!-- The amount of the peeking card showing above the fold with the increased visibility UI
          (https://crbug.com/660837). -->
     <dimen name="snippets_peeking_card_peek_amount">32dp</dimen>
     <dimen name="snippets_peeking_card_bounce_distance">10dp</dimen>
     <dimen name="snippets_card_gap">0.5dp</dimen>
     <dimen name="snippets_article_header_height">40dp</dimen>
@@ skipping 120 matching lines @@
     <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>
 
     <!-- Context Menu Dimensions -->
     <dimen name="context_menu_header_image_min_size">56dp</dimen>
     <dimen name="context_menu_header_image_max_size">56dp</dimen>
 </resources>