[tool] SpnegoAuth: add multi account, credential confirmation

tools/android/kerberos/SpnegoAuthenticator/AndroidManifest.xml

 <?xml version="1.0" encoding="utf-8"?>
 <!--
   Copyright (c) 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.
 -->
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="org.chromium.tools.spnegoauthenticator" >
 
     <uses-sdk android:minSdkVersion="21" android:targetSdkVersion="23" />
 
+    <!--
+      Deprecated permissions. Normal protection level, autogranted. Needed
+      for API level 22 and before.
+    -->
     <uses-permission android:name="android.permission.AUTHENTICATE_ACCOUNTS" />
     <uses-permission android:name="android.permission.MANAGE_ACCOUNTS" />
 
     <application
         android:allowBackup="true"
         android:icon="@mipmap/ic_launcher"
         android:label="@string/app_name" >
         <service
             android:name=".SpnegoAuthenticatorService"
             android:exported="true" >
             <intent-filter>
                 <action android:name="android.accounts.AccountAuthenticator" />
             </intent-filter>
 
             <meta-data
                 android:name="android.accounts.AccountAuthenticator"
                 android:resource="@xml/spnego_authenticator" />

[dgn, 2015/11/11 12:05:31]

I tried to remove my code to show the notification and send the broadcast
intent, and add <meta-data
android:name="android.accounts.AccountAuthenticator.customTokens"
android:value="1" /> here instead, hoping that it would make the framwork take
care of it. That didn't work, I don't seem to get anything, it behaves the same
as without the flag.

According to the code at http://go/dgn-review-androidauth-1
it looks like I should have customTokens to false if I want that to work. Am I
looking at the wrong thing?

         </service>
+
+        <!-- exported=true needed so that chrome can start the activity -->
+        <activity
+           android:exported="true"
+           android:label="@string/title_activity_account_authenticator"
+           android:name=".SpnegoAuthenticatorActivity"
+           android:noHistory="true">
+       </activity>
     </application>
 
 </manifest>