Issue 6574 - Sign in option being shown on tablets

mobile/android/app/src/main/res/xml/preferences_general_tablet.xml

 <?xml version="1.0" encoding="utf-8"?>
 <!-- This Source Code Form is subject to the terms of the Mozilla Public
    - License, v. 2.0. If a copy of the MPL was not distributed with this
    - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
 
 <!-- Tablet only: The contents under the "General" header for tablets,
      See xml-v11/preferences.xml for single-pane v11+ phone layout.
      Changes to preferences should be mirrored to preferences_general.xml. -->
 
 <PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
                   android:title="@string/pref_category_general"
                   android:enabled="false">
 
-    <org.mozilla.gecko.preferences.SyncPreference android:key="android.not_a_preference.sync"
-                                                  android:title="@string/pref_sync"
-                                                  android:persistent="false" />
+    <!-- Removed Sync Preference. See https://issues.adblockplus.org/ticket/6574 -->
 
     <PreferenceScreen android:key="android.not_a_preference.general_home"
                       android:title="@string/pref_category_home"
                       android:summary="@string/pref_category_home_summary"
                       android:fragment="org.mozilla.gecko.preferences.GeckoPreferenceFragment" >
             <extra android:name="resource"
                    android:value="preferences_home" />
     </PreferenceScreen>
 
     <PreferenceScreen android:title="@string/pref_category_language"
                       android:summary="@string/pref_category_language_summary"
                       android:fragment="org.mozilla.gecko.preferences.GeckoPreferenceFragment" >
         <extra android:name="resource"
                android:value="preferences_locale" />
     </PreferenceScreen>
 
     <SwitchPreference android:key="browser.chrome.dynamictoolbar"
                       android:title="@string/pref_scroll_title_bar2"
                       android:summary="@string/pref_scroll_title_bar_summary" />
 
     <SwitchPreference android:key="android.not_a_preference.tab_queue"
                       android:title="@string/pref_tab_queue_title"
                       android:summary="@string/pref_tab_queue_summary"
                       android:defaultValue="false" />
 
 </PreferenceScreen>