Update account and sync management UX

chrome/android/java/res/xml/sync_customization_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">
 
     <org.chromium.chrome.browser.preferences.ChromeSwitchPreference
         android:key="sync_switch"
-        android:summaryOn="@string/text_on"
-        android:summaryOff="@string/text_off" />
+        android:title="@string/sign_in_sync"
+        android:summary="@string/sync_description" />
+
+    <org.chromium.chrome.browser.preferences.SyncAccountListPreference
+        android:key="sync_account_list"
+        android:title="@string/sync_to_account_header"

[newt (away), 2016/02/12 22:03:50]

I'd suggest setting the title and summary in Java, so that all the logic related
to this preference lives in SyncAccountListPreference.java, rather than having a
small bit of the logic live in the xml file.

[May, 2016/02/16 17:32:06]

Done.

+        android:summary="%s" />
 
     <PreferenceCategory
         android:key="sync_data_types"
         android:title="@string/sync_data_types">
         <org.chromium.chrome.browser.preferences.ChromeSwitchPreference
             android:persistent="false"
             android:key="sync_everything"
             android:title="@string/sync_everything_pref"/>
         <org.chromium.chrome.browser.preferences.ChromeBaseCheckBoxPreference
             android:persistent="false"
@@ skipping 26 matching lines @@
     </PreferenceCategory>
     <Preference
         android:key="encryption"
         android:title="@string/sync_encryption">
     </Preference>
     <Preference
         android:key="sync_manage_data"
         android:title="@string/sync_manage_data">
     </Preference>
 </PreferenceScreen>