Require explicit user action for shipping address.

chrome/android/java/res/layout/payment_request.xml

 <?xml version="1.0" encoding="utf-8"?>
 <!--
    Copyright 2016 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.
 -->
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:orientation="vertical">
 
@@ skipping 133 matching lines @@
 
             <TextView
                 android:id="@+id/shippingAddressesLabel"
                 android:layout_height="wrap_content"
                 android:layout_width="match_parent"
                 android:textColor="#0000ff"
                 android:text="@string/payments_shipping_address_label"
                 android:padding="16dp"
                 android:visibility="gone" />
 
+            <TextView
+                android:id="@+id/selectShippingAddressPrompt"
+                android:layout_height="wrap_content"
+                android:layout_width="match_parent"
+                android:text="@string/payments_select_shipping_address_prompt"
+                android:padding="16dp"
+                android:visibility="gone" />
+
             <RadioGroup
                 android:id="@+id/shippingAddresses"
                 android:layout_height="wrap_content"
                 android:layout_width="match_parent"
                 android:orientation="vertical"
                 android:padding="16dp"
                 android:visibility="gone">
 
             </RadioGroup>
 
@@ skipping 120 matching lines @@
 
         <TextView
             android:id="@+id/waitingMessage"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:text="@string/payments_processing_message"
             android:textColor="@color/light_active_color"
             android:textSize="20sp" />
     </LinearLayout>
 </LinearLayout>