Update account and sync management UX

chrome/android/java/res/values-v21/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>
     <!-- Preferences -->
     <style name="PreferencesTheme" parent="ThemeWithActionBar">
         <item name="android:textColorLink">@color/pref_accent_color</item>
         <item name="android:alertDialogTheme">@style/PreferencesDialogTheme</item>
+        <item name="android:divider">@null</item>
         <item name="android:spinnerItemStyle">@style/PreferenceSpinnerItem</item>
         <item name="floatLabelTextAppearance">@style/PreferenceFloatLabelTextAppearance</item>
         <item name="floatLabelPaddingLeft">@dimen/pref_autofill_field_horizontal_padding</item>
         <item name="floatLabelPaddingRight">@dimen/pref_autofill_field_horizontal_padding</item>
         <item name="floatLabelPaddingTop">@dimen/pref_autofill_field_top_padding</item>
     </style>
     <style name="PreferencesDialogTheme" parent="@android:style/Theme.Material.Light.Dialog.Alert">
         <item name="android:colorAccent">@color/pref_accent_color</item>
     </style>
     <style name="PreferenceCategoryWithButtonStyle">
@@ skipping 108 matching lines @@
         <item name="android:popupWindowStyle">@style/ListPopupWindow.LowEnd</item>
         <item name="android:listPopupWindowStyle">@style/ListPopupWindow.LowEnd</item>
         <item name="android:spinnerStyle">@style/Spinner.LowEnd</item>
         <item name="android:autoCompleteTextViewStyle">@style/AutoCompleteTextView.LowEnd</item>
 
         <!-- Without HW acceleration the default text cursor looks weird (top
              half is way brighter than the bottom), so we use our own. -->
         <item name="android:textCursorDrawable">@drawable/text_cursor_lowend</item>
     </style>
 </resources>