Add icon to the Data Saver main menu footer and update to spec

chrome/android/java/res/values-v17/styles.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 xmlns:tools="http://schemas.android.com/tools">
     <!-- Q: Why put style resources under values-v17/ ?
          A: Problem:
             1. paddingStart causes a crash on Galaxy Tab&Note b/8351339.
             2. So we wrote a build script(generate_v14_compatible_resources.py) to convert
@@ skipping 148 matching lines @@
         <item name="android:textAppearance">@style/PreferenceTextAppearanceMedium</item>
     </style>
     <style name="PreferenceSpinnerUnderlineView">
         <item name="android:layout_width">match_parent</item>
         <item name="android:layout_height">1dp</item>
         <item name="android:layout_marginTop">2dp</item>
         <item name="android:background">@color/google_grey_600</item>
     </style>
     <style name="Divider">
         <item name="android:layout_width">match_parent</item>
-        <item name="android:layout_height">1dp</item>
+        <item name="android:layout_height">@dimen/divider_height</item>
         <item name="android:background">@color/google_grey_300</item>
     </style>
 
     <style name="ThemeWithActionBar" parent="Theme.AppCompat.Light.DarkActionBar">
         <item name="android:windowBackground">@drawable/action_bar_activity_bg</item>
         <!-- Action bar color -->
         <item name="colorPrimary">@color/dark_action_bar_color</item>
         <!-- Status bar color -->
         <item name="colorPrimaryDark">#161e21</item>
         <!-- Color of checkboxes, switches, buttons, etc. -->
@@ skipping 486 matching lines @@
         <item name="android:contentDescription">@null</item>
         <item name="android:scaleType">center</item>
         <item name="android:background">@color/light_active_color</item>
     </style>
 
     <!-- Miscellaneous -->
     <style name="BottomSheetContentTitle" parent="TextAppearance.Widget.AppCompat.Toolbar.Title">
         <item name="android:textSize">20sp</item>
     </style>
 </resources>