Remove special theming for CardUnmaskPrompt since it's now automatic

chrome/android/java/res/values/colors.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>
     <!-- Common colors -->
     <color name="default_text_color">#333</color>
     <color name="default_primary_color">#f2f2f2</color>
     <color name="light_normal_color">#5A5A5A</color>
     <color name="light_active_color">#4285F4</color>
     <color name="input_underline_color">#e5e5e5</color>
     <color name="input_underline_error_color">#d32f2f</color>
     <color name="explanation_text_color">#909090</color>
-    <color name="text_highlight_color">#C6DAFC</color>
 
     <!-- Infobar colors -->
     <color name="infobar_background">#fff</color>
     <color name="infobar_background_separator">#afafaf</color>
     <color name="infobar_accent_blue">#4285f4</color>
     <color name="infobar_tertiary_button_text">#969696</color>
 
     <!-- Tab Switcher Colors -->
     <color name="tab_switcher_background">#111111</color>
     <color name="accessibility_tab_switcher_list_item">#252525</color>
@@ skipping 51 matching lines @@
     <!-- NTP Colors. Used on the bookmarks and recent tabs pages. -->
     <color name="ntp_bg">#fff</color>
 
     <!-- Signin promo screen colors -->
     <color name="illustration_background_color">#4FC3F7</color>
 
     <!-- Contextual Search colors -->
     <color name="contextual_search_promo_text_color">#333333</color>
     <color name="contextual_search_promo_background_color">#EEEEEE</color>
 </resources>