Use PreferenceCategory instead of manual preference ordering

chrome/android/java/res/xml/account_management_preferences.xml

 <?xml version="1.0" encoding="utf-8"?>
 <!-- Copyright 2015 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. -->
 
 <PreferenceScreen
     xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
-    android:orderingFromXml="false">
+    xmlns:app="http://schemas.android.com/apk/res-auto">
 
     <PreferenceCategory
-        android:title="@string/account_management_title"
-        android:order="0" />
-
-    <!-- Google accounts will be inserted here, using order values starting at 100 -->
-
-    <org.chromium.chrome.browser.preferences.ChromeBasePreference
-        android:key="add_account"
-        android:icon="@drawable/add_circle_blue"
-        android:order="1000" />
+        android:key="accounts_category"
+        android:title="@string/account_management_title"/>
 
     <Preference
-        android:layout="@layout/divider_preference"
-        android:order="1001" />
+        android:layout="@layout/divider_preference"/>
 
     <PreferenceCategory
         android:key="parental_settings"
-        android:title="@string/account_management_parental_settings"
-        android:order="1002" />
+        android:title="@string/account_management_parental_settings"/>
 
     <org.chromium.chrome.browser.preferences.ChromeBasePreference
-        android:key="parent_accounts"
-        android:order="1003" />
+        android:key="parent_accounts"/>
 
     <Preference
         android:key="child_content"
-        android:title="@string/account_management_child_content_title"
-        android:order="1004" />
+        android:title="@string/account_management_child_content_title"/>
 
     <Preference
         android:key="child_content_divider"
-        android:layout="@layout/divider_preference"
-        android:order="1005" />
+        android:layout="@layout/divider_preference"/>
 
     <org.chromium.chrome.browser.preferences.SyncPreference
         android:key="sync_settings"
-        android:title="@string/sign_in_sync"
-        android:order="1006" />
+        android:title="@string/sign_in_sync"/>
 
     <Preference
-        android:layout="@layout/divider_preference"
-        android:order="1007" />
+        android:layout="@layout/divider_preference"/>
 
     <Preference
         android:key="google_activity_controls"
         android:icon="@drawable/googleg"
         android:title="@string/sign_in_google_activity_controls"
-        android:summary="@string/sign_in_google_activity_controls_message"
-        android:order="1008" />
+        android:summary="@string/sign_in_google_activity_controls_message"/>
 
     <Preference
-        android:layout="@layout/divider_preference"
-        android:order="1009" />
+        android:layout="@layout/divider_preference"/>
 
     <Preference
         android:key="sign_out"
-        android:title="@string/account_management_sign_out"
-        android:order="1010" />
+        android:title="@string/account_management_sign_out"/>
 
     <Preference
         android:key="sign_out_divider"
-        android:layout="@layout/divider_preference"
-        android:order="1011" />
+        android:layout="@layout/divider_preference"/>
 
 </PreferenceScreen>