Add UI hook for distilling web pages for test shell (relanding)

chrome/android/shell/res/menu/main_menu.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.
 -->
 
 <menu xmlns:android="http://schemas.android.com/apk/res/android">
     <group android:id="@+id/MAIN_MENU"
            android:visible="false">
         <item android:id="@+id/signin"
               android:title="@string/signin_sign_in" />
         <item android:id="@+id/print"
               android:title="@string/print_menu" />
+        <item android:id="@+id/distill_page"
+              android:title="@string/distill_page_menu" />
     </group>
 
     <group android:id="@+id/PHONE_ICON_MENU_ITEMS"
         android:visible="false">
         <!-- These items are never made visible in the default list. They are only used
              to pass through the clicks from the icon row in the custom menu. -->
         <item android:id="@+id/back_menu_id"
             android:title="@null" />
         <item android:id="@+id/forward_menu_id"
             android:title="@null" />
         <item android:id="@+id/bookmark_this_page_id"
             android:title="@null" />
     </group>
 </menu>